0001140361-23-053917 | S-1/A | XBRL Viewer | American Oncology Network INC

7. Inventories

Inventories consisted of the following at December 31, 2022 and 2021:

	As of December 31,
	2022	2021
Intravenous drugs	$25,674	$28,897
Oral pharmaceuticals	10,802	5,632
Total inventories	$36,476	$34,529

Leases, Maturity of Operating and Finance Lease (FY) (Details) - USD ($)
$ in Thousands

Sep. 30, 2023

Dec. 31, 2022

Dec. 31, 2021

Operating Leases [Abstract]

2023

$ 10,940

$ 11,215

9,830

10,049

9,413

7,762

8,194

7,448

6,528

11,067

64,210

54,069

(14,826)

(7,668)

49,384

46,401

Long-term lease liabilities, net of current portion

(7,123)

^[1]

(9,177)

^[1],[2]

$ 0

^[2]

42,261

^[3]

37,224

^[3],[4]

^[4]

Finance Leases [Abstract]

2023

753

491

731

491

492

469

428

231

166

429

3,120

2,277

(364)

(233)

2,756

2,044

Long-term lease liabilities, net of current portion

(630)

(425)

$ 0

$ 2,126

$ 1,619

[1]	Includes related party current portion of operating lease liabilities of $1,912 and $1,836 at September 30, 2023 and December 31, 2022, respectively
[2]	Includes related party current portion of operating lease liabilities of $1,836 at December 31, 2022
[3]	Includes related party long-term operating lease liabilities of $9,994 and $11,631 at September 30, 2023 and December 31, 2022, respectively
[4]	Includes related party long-term operating lease liabilities of $11,631 at December 31, 2022

Net Loss Per Share - Calculation Of Earnings Per Share (Q3) (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss attributable to Class A Common Stockholders for basic loss per share	$ 1,792,000	$ 0	$ 1,792,000	$ 0
Net loss attributable to Class A Common Stockholders for diluted loss per share	$ 1,792,000	$ 0	$ 1,792,000	$ 0	$ 0	$ 0	$ 0
Weighted average shares for basic loss per share (in shares)	6,614,229	0	6,614,229	0
Weighted average shares for diluted loss per share (in shares)	6,614,229	0	6,614,229	0
Earnings (loss) per common unit, basic (in dollars per share)	$ (0.61)	$ 0	$ (0.61)	$ 0	$ 0	$ 0	$ 0
Earnings (loss) per common unit, diluted (in dollars per share)	$ (0.61)	$ 0	$ (0.61)	$ 0	$ 0	$ 0	$ 0
Common Class A
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss attributable to Class A Common Stockholders for basic loss per share			$ 1,791,768
Net loss attributable to Class A Common Stockholders for diluted loss per share			1,791,768
Undistributed net loss, dilutive			4,013,000
Undistributed net earnings, basic			4,013,000
Weighted average shares for basic loss per share (in shares)					0	0	0
Weighted average shares for diluted loss per share (in shares)					0	0	0
Earnings (loss) per common unit, basic (in dollars per share)					$ 0	$ 0	$ 0
Earnings (loss) per common unit, diluted (in dollars per share)					$ 0	$ 0	$ 0
Series A Preferred Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Series A Deemed Dividend			(2,089,000)
Series A Preferred Cumulative Dividends			$ (133,032)

Summary of Significant Accounting Policies and Basis of Presentation, Property and Equipment (FY) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Long-lived asset impairments	$ 0	$ 0	$ 0
Leasehold Improvements [Member] \| Minimum [Member]
Property, Plant and Equipment [Abstract]
Estimated useful lives	1 year
Leasehold Improvements [Member] \| Maximum [Member]
Property, Plant and Equipment [Abstract]
Estimated useful lives	15 years
Furniture, Fixtures and Equipment [Member]
Property, Plant and Equipment [Abstract]
Estimated useful lives	7 years
Medical Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Abstract]
Estimated useful lives	5 years
Medical Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Abstract]
Estimated useful lives	10 years
Computer Equipment [Member]
Property, Plant and Equipment [Abstract]
Estimated useful lives	5 years
Signs [Member]
Property, Plant and Equipment [Abstract]
Estimated useful lives	7 years
Automobiles [Member]
Property, Plant and Equipment [Abstract]
Estimated useful lives	5 years
Software [Member]
Property, Plant and Equipment [Abstract]
Estimated useful lives	7 years

Leases, Weighted-average Remaining Lease Terms and Discount Rates (FY) (Details)	Sep. 30, 2023	Dec. 31, 2022
Weighted-average Remaining Lease Terms and Discount Rates [Abstract]
Weighted-average remaining operating lease term	7 years 3 days	5 years 8 months 4 days
Weighted-average remaining finance lease term	5 years	5 years 4 months 13 days
Operating leases weighted-average discount rate	6.56%	4.88%
Finance leases weighted-average discount rate	5.12%	3.60%

Business (FY) (Tables)

12 Months Ended

Dec. 31, 2022

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships

During the years ended December 31, 2022, 2021, and 2020, respectively, the Company entered into affiliation agreements with or acquired the following oncology practices. The operations of the practices that were acquired have been included in the Company’s consolidated financial statements since the date of acquisition. The Company intends to continue to pursue additional purchases of physician practices in addition to seeking out new affiliation relationships.

State

Effective

Date

State

Effective

Date

State

Effective

Date

Location 12

North

Carolina

4/1/2020

Location 18

Maryland

3/1/2021

Location 23

Arizona

1/1/2022

Location 13

Maryland

5/1/2020

Location 19

Arizona

4/1/2021

Location 24

Georgia^(a)

1/1/2022

Location 14

Virginia

5/1/2020

Location 20

Washington

5/1/2021

Location 25

Louisiana^(a)

1/17/2022

Location 15

Michigan

7/1/2020

Location 21

Georgia^(a)

8/1/2021

Location 26

Georgia^(a)

4/5/2022

Location 16

Washington

8/1/2020

Location 22

Arizona

11/1/2021

Location 27

Georgia^(a)

5/1/2022

Location 17

Georgia and

South

Carolina

9/1/2020

Location 28

Georgia^(a)

9/20/2022

(a)	The Company entered into affiliation agreements with the physicians for these respective practices. The Company evaluated each of the affiliation agreements and determined that the transactions did not represent a business combination.

Summary of Significant Accounting Policies and Basis of Presentation, Segments (FY) (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2023 segment	Dec. 31, 2022 Segment
Segments [Abstract]
Number of operating segments	1	1
Number of reportable segments	1	1

Fair Value Measurements, Financial Assets Measured at Fair Value on Recurring Basis (FY) (Details) - USD ($)
$ in Thousands

Sep. 30, 2023

Dec. 31, 2022

Financial Assets Measured at Fair Value [Abstract]

$ 114

$ 12

(42)

(129)

Marketable Securities [Member]

26,034

9,851

Financial Assets Measured at Fair Value [Abstract]

Financial Assets Measured at Fair Value [Abstract]

9,851

Corporate Bonds [Member]

U.S. Treasury Securities [Member]

7,623

Financial Assets Measured at Fair Value [Abstract]

Financial Assets Measured at Fair Value [Abstract]

2,228

Level 2 [Member]

25,961

9,968

114

(42)

(129)

Financial Assets Measured at Fair Value [Abstract]

$ 26,033

9,851

Recurring [Member]

10,077

(129)

Recurring [Member] | Level 1 [Member] | Money Market Funds [Member]

9,960

Financial Assets Measured at Fair Value [Abstract]

^[1]

109

^[1]

^[1]

Recurring [Member] | Level 2 [Member] | Marketable Securities [Member]

^[1]

109

Financial Assets Measured at Fair Value [Abstract]

9,968

(129)

Recurring [Member] | Level 2 [Member] | Corporate Bonds [Member]

9,851

Financial Assets Measured at Fair Value [Abstract]

7,742

(125)

Recurring [Member] | Level 2 [Member] | U.S. Treasury Securities [Member]

7,623

Financial Assets Measured at Fair Value [Abstract]

2,226

(4)

Property and Equipment, Net [Abstract]

$ 2,228

[1]	Included in cash and cash equivalents in the Consolidated Balance Sheet at December 31, 2022

Property and Equipment, Net (FY) (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Property and Equipment, Net

Property and equipment, net consisted of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
Leasehold improvements	$30,078	$26,076
Furniture, fixtures and equipment	2,722	2,669
Medical equipment	12,659	11,003
Computer equipment	3,325	3,115
Signs	147	129
Automobiles	59	69
Software	4,412	4,834
Construction-in-progress	6,150	1,433
Property and equipment, gross	59,552	49,328
Accumulated depreciation and amortization	(23,312)	(17,348)
Property and equipment, net	$36,240	$31,980

Property and equipment, net, consisted of the following at December 31, 2022 and 2021:

	As of December 31,
	2022	2021
Leasehold improvements	$26,076	$23,744
Furniture, fixtures and equipment	2,669	2,346
Medical equipment	11,003	8,811
Computer equipment	3,115	2,713
Signs	129	117
Automobiles	69	69
Software	4,834	4,036
Construction-in-progress	1,433	1,445
	49,328	43,281
Accumulated depreciation and amortization	(17,348)	(10,633)
Property and equipment, net	$31,980	$32,648

Condensed Consolidated Statements of Cash Flows (Q3) - USD ($)
$ in Thousands

9 Months Ended

Sep. 30, 2023

Sep. 30, 2022

Cash flows from operating activities

Net income (loss) before noncontrolling interest

$ (40,797)

$ 1,227

Adjustments to reconcile net income (loss) to net cash provided by operating activities

Depreciation and amortization

6,368

5,318

Amortization of debt issuance costs

570

458

Deferred income taxes

Amortization of operating right-of-use assets

^[1]

6,194

7,766

Changes in fair value adjustments of warrants and derivative liabilities

9,334

Equity-based compensation

4,875

Equity in loss of affiliate

251

Gain on sale of property and equipment

(2)

Changes in operating assets and liabilities, net of reverse recapitalization:

(4,941)

(15,223)

^[2]

(1,367)

876

(775)

641

(8,546)

(211)

(2,107)

(376)

^[3]

13,889

9,586

8,744

4,456

6,290

(1,563)

Medicare advance payments

^[4]

(5,625)

(8,252)

(3,742)

Net cash (used in) provided by operating activities

1,410

654

(6,160)

1,630

Cash flows from investing activities

Purchase of property and equipment

(9,527)

(5,051)

Proceeds from disposals of property and equipment

1,137

Purchases of marketable securities

(20,824)

(11,949)

Proceeds from sales of marketable securities

4,933

1,956

Issuance of notes receivable - related parties

(243)

Collections on notes receivable - related parties

740

1,091

Net cash used in investing activities

(24,673)

(13,059)

Cash flows from financing activities

Borrowings on long-term debt

16,250

Issuance of redeemable convertible Class C Units

64,996

Class A and A-1 preferred returns and tax distributions

(9,481)

Repayments on finance lease liabilities

(387)

(321)

Contribution from noncontrolling interest

134

Cash paid for debt financing costs

(446)

(171)

Proceeds from reverse recapitalization

1,494

Net cash provided by financing activities

55,560

15,758

Net (decrease) increase in cash and cash equivalents and restricted cash

24,727

4,329

Cash and cash equivalents, Beginning of Period

26,926

32,354

Cash and cash equivalents, End of Period

51,653

36,683

Supplemental noncash investing and financing activities

Unpaid offering costs relating to the reverse recapitalization

2,745

Right-of-use assets and lease liabilities removed in termination of lease

1,254

Deemed Divided for Series A Preferred Stock Extinguishment

2,089

Changes in accounts payable for capital additions to property and equipment

159

Disposal of property and equipment in exchange for reduction in finance lease liability

Series A Preferred Stock

Cash flows from financing activities

Offering costs

$ (750)

$ 0

[1]	Includes related party amortization of operating right-of-use assets of $1,601 and $1,536 for the nine months ended September 30, 2023 and 2022, respectively.
[2]	Includes changes in related party balances of ($1,299) and $832 for the nine months ended September 30, 2023 and 2022, respectively.
[3]	Includes changes in related party balances of $10,627 and $23,309 for the nine months ended September 30, 2023 and 2022, respectively.
[4]	Includes changes in related party balances of ($1,835) and ($1,446) for the nine months ended September 30, 2023 and 2022, respectively.

Leases, Components of Lease Costs (FY) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Components of Lease Costs [Abstract]
Operating lease costs	$ 2,820	$ 3,161	$ 8,361	$ 9,297	$ 12,465
Finance lease costs [Abstract]
Amortization of finance lease right-of-use assets	122	185	354	413	523
Interest on finance lease liabilities (included in interest expense)	35	19	79	60	79
Variable lease costs	560	862	1,742	2,232	2,737
Total lease costs	$ 3,537	$ 4,227	$ 10,536	$ 12,002	$ 15,804

Variable Interest Entities - Narrative (Q3) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	9 Months Ended
	May 31, 2023	Jun. 30, 2023	Sep. 30, 2023
AON Central
Variable Interest Entity [Line Items]
Ownership interest			20.00%
MIBA
Variable Interest Entity [Line Items]
Payments to acquire interest in subsidiary	$ 0.2	$ 0.2
Allocation of income to controlling and noncontrolling interests	56.00%
MIBA \| Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Allocation of income to controlling and noncontrolling interests		56.00%
Physician Owned \| AON Central
Variable Interest Entity [Line Items]
Ownership interest			80.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Long-term Debt - Schedule of Long-term Debt (Q3) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Total	$ 81,250	$ 81,250	$ 65,000
Unamortized debt issuance costs	(825)	(949)
Total debt	80,425	80,301
PNC Loan Facility [Member]
Debt Instrument [Line Items]
Total		81,250	$ 65,000
PNC Loan Facility [Member] \| Line of Credit
Debt Instrument [Line Items]
Total	$ 81,250	$ 81,250

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

Reverse Capitalization (Q3)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Reverse Recapitalization [Abstract]

Reverse Recapitalization

3. Reverse Recapitalization

As discussed in Note 1, AON LLC merged with DTOC, with AON LLC surviving the Merger. AON LLC is governed by a board of managers composed of three (3) persons that were designated by New AON and two (2) persons that were designated by holders of a majority of the AON LLC Common Units, held by members of AON LLC other than New AON. Management determined AON LLC was not a variable interest entity (Refer to Note 2), and as result, identified AON LLC as the accounting acquirer of the Merger in accordance ASC Topic 805. Management concluded that AON LLC was the accounting acquirer due to (i) the Legacy AON Shareholders, defined as the former AON Class A, Class A-1, and Class B unit holders, receiving the largest portion of the voting rights in the combined company, New AON, (ii) significantly all of the Legacy AON Shareholders retained their equity interest as stockholders in New AON, (iii) AON LLC’s operations prior to the Reverse Recapitalization comprising the only ongoing operations of New AON, (iv) the Legacy AON Shareholders have the right to appoint a majority of the directors of New AON, (v) the executive management of AON LLC will become the executive management of New AON and (vi) AON LLC is significantly larger than New AON in terms of revenue, total assets, and employees. Therefore, the Merger was accounted for as a reverse recapitalization, with no goodwill or other intangible assets recorded, in accordance with ASC Topic 805. New AON was treated as the “acquired” company for financial reporting purposes, and for accounting purposes, the Reverse Recapitalization was treated as the equivalent of AON LLC issuing stock for the net assets of New AON, accompanied by a recapitalization. The net assets of New AON were recorded at historical cost on the condensed consolidated balance sheet as of September 20, 2023, the Closing Date of the Reverse Recapitalization, with no goodwill or other intangible assets recorded. For additional information on the capitalization of New AON and AON LLC immediately following the Closing of the Reverse Recapitalization, see Note 1.

The following table provides the historical cost of assets and liabilities of AON Inc. as of September 20, 2023.

			As of September 30, 2023
Cash and Cash Equivalents			$1,493
Current Liabilities			(13,295)
Long Term Liabilities			(6,791)
Total Net Liabilities			$(18,593)

The Company recorded a Day 1 expense as of the Closing of the Business Combination equal to $18.2 million. Of that total amount, $13.0 million was recorded in transaction expenses on the condensed consolidated statement of operations and comprehensive loss. The remaining $5.2 million was recorded in other income (expense) net on the condensed consolidated statement of operations and comprehensive loss. This amount represented the loss on the issuance of Public and Private Warrants, as of the Closing, net of cash received. The Company also recorded a $4.3 million gain in other income (expense), net related to the change in the fair value of the Public and Private Warrants during the period of September 21, 2023 through September 30, 2023.

2. Reverse Recapitalization

Business Combination Agreement

Digital Transformation Opportunities Corp. (“DTOC”), American Oncology Network, LLC (“AON LLC”), GEF AON Holdings Corp. (“AON Class C Preferred Investor”), and DTOC Merger Sub, Inc., a direct, wholly owned subsidiary of DTOC (“Merger Sub”) entered into a Business Combination Agreement (the “Business Combination Agreement”), dated as of June 14, 2023 (which further amended and restated the Business Combination Agreement entered into by DTOC and AON as of October 5, 2022, and amended and restated on January 6, 2023, and April 27, 2023), pursuant to which, among other transactions, on September 20, 2023 (the “Closing Date”), DTOC and AON undertook a series of transactions (the “Reverse Recapitalization” or the “Business Combination”) resulting in the organization of the combined post-business combination company as an umbrella partnership C corporation, in which substantially all of the assets and the business of the combined company are held by AON LLC, and DTOC became a member of AON LLC. In connection with the closing of the Business Combination (“the Closing”), DTOC changed its name to “American Oncology Network, Inc.”. The Business Combination was completed on September 20, 2023.

Series A Preferred Units”); (ii) AON LLC converted profit pool units of certain of AON LLC’s subsidiaries into an equal number of AON LLC Common Units and shares of New AON Class B common stock (“New AON Class B Common Stock”), which together are exchangeable into shares of New AON Class A Common Stock (together with the New AON Class B Common Stock, the “New AON Common Stock”); (iii) New AON amended and restated its charter (the “Charter”) to provide for (a) the conversion of all existing shares of DTOC Class B common stock into shares of New AON Class A Common Stock on a one-to-one basis, (b) amendment of the terms of New AON Class B Common Stock to provide holders voting rights but no economic rights and (c) designation of a new series of New AON preferred stock as Series A convertible preferred stock (the “New AON Series A Preferred Stock” or “Series A Preferred Stock”) with such rights and preferences as provided for in the certificate of designation of the New Aon Series A Preferred Stock (the “New AON Series A Certificate of Designation”); and (iv) among other things, (a) AON LLC issued common units to New AON in exchange for a combination of cash and shares of New AON Class B Common Stock and warrants to acquire shares of New AON Class B Common Stock (the “Class B Prefunded Warrants”), (b) New AON was admitted as a member of AON LLC, (c) AON LLC distributed shares of New AON Class B common stock or Class B Prefunded Warrants, as applicable, to AON LLC equity holders, (d) New AON reserved a specified number of additional shares of New AON Class A Common Stock after the Closing for issuance to eligible participants, (e) Merger Sub merged with and into the AON Class C Preferred Investor whereby the separate existence of Merger Sub ceased and New AON issued a number of shares of New AON Series A Preferred Stock equal to the number of AON LLC Series A preferred units held by the AON Class C Preferred Investor to AEA Growth Management LP, the parent of AON Class C Preferred Investor (“AEA Growth”) in exchange for all the shares of common stock held by AEA Growth in the AON Class C Preferred Investor (the “First Step”), (f) promptly after the First Step, the AON Class C Preferred Investor merged with and into New AON whereby the separate existence of the AON Class C Preferred Investor ceased and New AON held all the AON LLC Series A preferred units and (g) from and after the Closing (but subject to lock-up restrictions), the AON LLC common equity holders (other than New AON), referred to herein as “Legacy AON Shareholders” (former AON LLC Class A, Class A-1, and Class B unit holders), will have the right (but not the obligation) to exchange AON LLC Common Units together with an equal number of shares of New AON Class B Common Stock (whether held directly or indirectly through Class B Prefunded Warrants) for shares of New AON Class A Common Stock.

In addition, in connection with the Closing, DTOC completed the offer to the holders of AON LLC Class B-1 units to exchange their AON LLC Class B-1 units for such number of newly issued shares of New AON Class A Common Stock equal to the ratio set forth in the Business Combination Agreement (such offer, the “Exchange Offer”). DTOC and AON LLC solicited consents from the holders of AON LLC Class B-1 units to make certain amendments to the terms of the awards and the unit grant agreements pursuant to which the AON LLC Class B-1 units were granted, which provided for the automatic exchange, as of immediately prior to the adoption of the Amended and Restated AON LLC Agreement, of all outstanding AON LLC Class B-1 units into shares of New AON Class A Common Stock (collectively, the “Proposed Amendments”). The requisite number of holders of Class B-1 units provided their consent to the Proposed Amendments, and as a result, in connection with the Closing, all AON LLC Class B-1 units were exchanged for an aggregate of 1,047,343 shares of New AON Class A Common Stock.

Reverse Recapitalization

AON LLC merged with DTOC, with AON LLC surviving the Merger. AON LLC is governed by a board of managers composed of three (3) persons that were designated by New AON and two (2) persons that were designated by holders of a majority of the AON LLC Common Units, held by members of AON LLC other than New AON. Management determined AON LLC was not a variable interest entity (Refer to Note 2), and as result, identified AON LLC as the accounting acquirer of the Merger in accordance ASC Topic 805. Management concluded that AON LLC was the accounting acquirer due to (i) the Legacy AON Shareholders, defined as the former AON Class A, Class A-1, and Class B unit holders, receiving the largest portion of the voting rights in the combined company, New AON, (ii) significantly all of the Legacy AON Shareholders retained their equity interest as stockholders in New AON, (iii) AON LLC’s operations prior to the Merger comprising the only ongoing operations of New AON, (iv) the Legacy AON Shareholders have the right to appoint a majority of the directors of New AON, (v) the executive management of AON LLC will become the executive management of New AON and (vi) AON LLC is significantly larger than New AON in terms of revenue, total assets, and employees. Therefore, the Merger was accounted for as a reverse recapitalization (the “Reverse Recapitalization”), with no goodwill or other intangible assets recorded, in accordance

with ASC Topic 805. New AON was treated as the “acquired” company for financial reporting purposes, and for accounting purposes, the Reverse Recapitalization was treated as the equivalent of AON LLC issuing stock for the net assets of New AON, accompanied by a recapitalization.

The Company recasted the units outstanding related to the historical AON LLC Class A, Class A-1, and Class B units prior to the Reverse Recapitalization (“Historical AON LLC Equity”) as common equity of New AON, equal to the Per Company Class Unit Exchange Ratio, pursuant to the Business Combination Agreement. The Per Company Unit Exchange Ratio at which AON LLC Class A units and Class A-1 units were reclassified is equal to 2,524 AON Common Units. The Per Company Unit Exchange Ratio at which AON LLC Class B units were reclassified varied depending on participation threshold, and is equal to 2,524, 2,453, or 1,976, AON Common Units. The Per Company Unit Exchange Ratio at which Class C units were reclassified is equal to 2,705 AON LLC Series A Preferred Units. Refer to Note 12 for Stockholders’ Equity and Note 18 for Earnings (Loss) per Share for additional disclosures updated to give effect to the Reverse Recapitalization.

Inventories (FY) (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Inventories [Abstract]

Inventory consisted of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
Intravenous drugs	$27,508	$25,674
Oral pharmaceuticals	10,336	10,802
Total inventories	$37,844	$36,476

Inventories consisted of the following at December 31, 2022 and 2021:

	As of December 31,
	2022	2021
Intravenous drugs	$25,674	$28,897
Oral pharmaceuticals	10,802	5,632
Total inventories	$36,476	$34,529

Accrued Other (FY) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Accrued Other [Abstract]
Refund liability	$ 14,521	$ 14,544	$ 8,306
Deferred social security taxes - COVID	0	378	378
Current portion of finance lease liability	630	425	0
Other		2,453	5,108
Total accrued other	$ 22,977	$ 17,800	$ 13,792

Leases (FY) (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Right-of-Use Assets and Lease Liabilities

Right-of-use assets and lease liabilities consist of the following at December 31, 2022:

Assets
Operating lease right-of-use assets, net			$43,724
Finance lease right-of-use assets, net (included in property and equipment, net)			1,998
Total right-of-use assets			$45,722
Liabilities
Current
Current portion of operating lease liabilities			$9,177
Current portion of finance lease liabilities (included in accrued other)			425
Long-term			9,602
Long-term operating lease liabilities			37,224
Long-term finance lease liabilities (included in other long-term liabilities)			1,619
Total lease liabilities			$48,445

Components of Lease Costs

The components of lease costs recognized in the condensed consolidated statements of operations and comprehensive loss consist of the following for the three and nine month periods ended September 30, 2023 and 2022 and are included in selling, general, and administrative expenses unless otherwise noted:

	Three Months Ended September 30,		Nine Months Ended September 30,
	2023	2022	2023	2022
Operating lease costs	$2,820	$3,161	$8,361	$9,297
Finance lease costs
Amortization of finance lease right-of-use assets	122	185	354	413
Interest on finance lease liabilities (included in interest expense)	35	19	79	60
Variable lease costs	560	862	1,742	2,232
Total lease costs	$3,537	$4,227	$10,536	$12,002

The cash paid for amounts included in the measurement of lease liabilities for the nine months ended September 30, 2023 and 2022 is as follows:

	Nine Months Ended September 30,
	2023	2022
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$7,678	$9,788
Operating cash flows from finance leases	79	60
Financing cash flows from finance leases	387	321
ROU assets obtained in exchange for new operating lease liabilities	9,862	9,771
ROU assets obtained in exchange for new finance lease liabilities	1,103	—

The components of lease costs recognized in the Consolidated Statements of Operations and Comprehensive Income (Loss) consist of the following for the year ended December 31, 2022:

Operating lease costs			$12,465
Finance lease costs
Amortization of finance lease right-of-use assets			523
Interest on finance lease liabilities (included in interest expense)			79
Variable lease costs			2,737
Total lease costs			$15,804

Maturity of Operating and Financing Leases

The following table reconciles the undiscounted cash flows expected to be paid in each of the next five years and thereafter recorded on the Consolidated Balance Sheet for operating and financing leases as of December 31, 2022:

	Operating Leases	Finance Leases
2023	$11,215	$491
2024	10,049	491
2025	7,762	469
2026	7,448	231
2027	6,528	166
Thereafter	11,067	429
Total lease payments	54,069	2,277
Less: amount representing interest	(7,668)	(233)
Present value of lease liabilities	46,401	2,044
Less: current portion of lease liabilities	(9,177)	(425)
Long-term lease liabilities, net of current portion	$37,224	$1,619

Cash Paid for Measurement of Lease Liabilities

The cash paid for amounts included in the measurement of lease liabilities for the year ended December 31, 2022 is as follows:

Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases			$12,590
Operating cash flows from finance leases			79
Financing cash flows from finance leases			426
ROU assets obtained in exchange for new operating lease liabilities			9,811

Leases - Narrative (Q3) (Details) $ in Millions	Sep. 30, 2023 USD ($) lease	Dec. 31, 2022
Leases [Abstract]
Weighted-average remaining lease term for operating leases	7 years 3 days	5 years 8 months 4 days
Weighted-average remaining lease term for finance leases	5 years	5 years 4 months 13 days
Weighted-average discount rate for operating leases (in percent)	6.56%	4.88%
Weighted-average discount rate for finance leases (in percent)	5.12%	3.60%
Finance lease not yet commenced, term of contract (in months)	60 months
Finance lease not yet commenced, number of leases \| lease	2
Leases not yet commenced, future commitments \| $	$ 3.8

Property and Equipment, Net (FY) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property and Equipment, Net [Abstract]
Property and equipment, gross	$ 49,328	$ 43,281
Accumulated depreciation and amortization	(17,348)	(10,633)
Property and equipment, net	31,980	32,648
Depreciation expense	6,700	6,100	$ 3,700
Leasehold Improvements [Member]
Property and Equipment, Net [Abstract]
Property and equipment, gross	26,076	23,744
Furniture, Fixtures and Equipment [Member]
Property and Equipment, Net [Abstract]
Property and equipment, gross	2,669	2,346
Medical Equipment [Member]
Property and Equipment, Net [Abstract]
Property and equipment, gross	11,003	8,811
Computer Equipment [Member]
Property and Equipment, Net [Abstract]
Property and equipment, gross	3,115	2,713
Signs [Member]
Property and Equipment, Net [Abstract]
Property and equipment, gross	129	117
Automobiles [Member]
Property and Equipment, Net [Abstract]
Property and equipment, gross	69	69
Software [Member]
Property and Equipment, Net [Abstract]
Property and equipment, gross	4,834	4,036
Construction-in-Progress [Member]
Property and Equipment, Net [Abstract]
Property and equipment, gross	$ 1,433	$ 1,445

Condensed Consolidated Statements of Mezzanine and Members' Equity (Q3) - USD ($) $ in Thousands	Total	Capital Unit, Class A	Capital Unit, Class A-1	Capital Unit, Class B	Common Class A	Common Class B	Common Stock Common Class A	Common Stock Common Class B	Common Units Capital Unit, Class A	Common Units Capital Unit, Class A-1	Common Units Capital Unit, Class B	Common Units Capital Unit, Class B-1	AOCI	Additional Paid in Capital	AOCI	Noncontrolling Interest	Retained Earnings (Deficit)
Beginning balance at Dec. 31, 2019	$ 9,158						$ 7,725	$ 40					$ 0				$ 1,393
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	0
Net income (loss) before noncontrolling interest	21,951						0	0					0				21,951
Net Income attributable to Legacy AON Shareholders	21,951
Ending balance at Dec. 31, 2020	59,629						7,725	$ 60					0				23,344
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity based compensation (in shares)								1,485
Other comprehensive income (loss)	0
Net income (loss) before noncontrolling interest	(105)						0	$ 0					0				(105)
Net Income attributable to Legacy AON Shareholders	(105)
Ending balance (in units) at Dec. 31, 2021					19,495,376	4,703,628			19,495,000	1,843,000
Ending balance at Dec. 31, 2021	59,544						7,725	80	$ 7,725	$ 28,500	$ 80		0				23,239
Increase (Decrease) In Noncontrolling Interest [Roll Forward]
Net loss attributable to noncontrolling interest	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated Other Comprehensive Income	(161)												(161)
Equity based compensation	15										15
Other comprehensive income (loss)	(161)
Net Income attributable to Legacy AON Shareholders	1,227																1,227
Ending balance (in units) at Sep. 30, 2022									19,495,000	1,843,000
Ending balance at Sep. 30, 2022	60,625								$ 7,725	$ 28,500	95		(161)				24,466
Ending Balance at Dec. 31, 2022
Ending Balance at Dec. 31, 2022
Beginning balance (in units) at Dec. 31, 2021					19,495,376	4,703,628			19,495,000	1,843,000
Beginning balance at Dec. 31, 2021	59,544						7,725	80	$ 7,725	$ 28,500	$ 80		0				23,239
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	(117)						0	0					(117)				0
Net income (loss) before noncontrolling interest	2,589						0	0					0				2,589
Net Income attributable to Legacy AON Shareholders	2,589
Ending balance (in units) at Dec. 31, 2022		19,495,376	1,842,520	4,703,628	19,495,376	4,703,628			19,495,000	1,843,000	4,704,000
Ending balance at Dec. 31, 2022	62,016						7,725	80	$ 7,725	$ 28,500	$ 80		(117)		$ (117)		25,828
Increase (Decrease) In Noncontrolling Interest [Roll Forward]
Net loss attributable to noncontrolling interest	0
Beginning balance (in units) at Jun. 30, 2022									19,495,000	1,843,000
Beginning balance at Jun. 30, 2022	55,090								$ 7,725	$ 28,500	90		(84)				18,859
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated Other Comprehensive Income	(77)												(77)
Equity based compensation	5										5
Other comprehensive income (loss)	(77)
Net Income attributable to Legacy AON Shareholders	5,607																5,607
Ending balance (in units) at Sep. 30, 2022									19,495,000	1,843,000
Ending balance at Sep. 30, 2022	$ 60,625								$ 7,725	$ 28,500	$ 95		(161)				24,466
Redeemable Preferred Stock
Issuance of Class C Units, net of offering costs (in shares)	6,500,000
Issuance of Class C Units, net of offering costs	$ 62,897
Beginning balance (in units) at Dec. 31, 2022		19,495,376	1,842,520	4,703,628	19,495,376	4,703,628			19,495,000	1,843,000	4,704,000
Beginning balance at Dec. 31, 2022	62,016						7,725	80	$ 7,725	$ 28,500	$ 80		(117)		(117)		25,828
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Class A and A-1 preferred returns	(8,174)																(8,174)
Issuance of additional Class A-1 Units pursuant to the Anti-Dilution Feature (in shares)										1,158,000
Issuance of additional Class A-1 Units pursuant to the Anti-Dilution Feature	9,725									$ 9,725
Tax distributions	(1,305)																(1,305)
Capital contribution from noncontrolling interest member	134															$ 134
Accumulated Other Comprehensive Income	178														178
Equity based compensation (in shares)											911,000	1,047,000
Equity based compensation	4,874										$ 10	$ 4,864
Net loss	(27,081)															(26)	(27,055)
Net Income attributable to Legacy AON Shareholders	(27,000)
Beginning Balance at Dec. 31, 2022
Ending Balance (in shares) at Sep. 30, 2023	6,652,000
Ending Balance at Sep. 30, 2023	$ 64,986
Beginning Balance at Dec. 31, 2022
Increase (Decrease) In Noncontrolling Interest [Roll Forward]
Net loss attributable to noncontrolling interest	(11,924)
Ending Balance at Sep. 30, 2023	369,329
Beginning balance (in units) at Dec. 31, 2022		19,495,376	1,842,520	4,703,628	19,495,376	4,703,628			19,495,000	1,843,000	4,704,000
Beginning balance at Dec. 31, 2022	62,016						$ 7,725	$ 80	$ 7,725	$ 28,500	$ 80		$ (117)		(117)		25,828
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	190
Net Income attributable to Legacy AON Shareholders	(27,081)
Fair value adjustment to redeemable noncontrolling interest														$ (17,600)			(326,700)
Ending balance (in shares) at Sep. 30, 2023					9,453,604	25,109,551	6,614,000	25,110,000
Ending balance (in units) at Sep. 30, 2023		0	0	0							0
Ending balance at Sep. 30, 2023	$ (341,223)						$ 1	$ 3						0	21	108	(341,356)
Beginning Balance (in shares) at Jun. 30, 2023	6,500,000
Beginning Balance at Jun. 30, 2023	$ 62,897
Ending Balance (in shares) at Sep. 30, 2023	6,652,000
Ending Balance at Sep. 30, 2023	$ 64,986
Increase (Decrease) In Noncontrolling Interest [Roll Forward]
Net loss attributable to noncontrolling interest	(11,924)
Ending Balance at Sep. 30, 2023	369,329
Beginning balance (in units) at Jun. 30, 2023									19,495,000	2,282,000	4,704,000
Beginning balance at Jun. 30, 2023	44,753								$ 7,725	$ 31,040	$ 80				(29)	134	5,803
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of additional Class A-1 Units pursuant to the Anti-Dilution Feature (in shares)										719,000
Issuance of additional Class A-1 Units pursuant to the Anti-Dilution Feature	7,185									$ 7,185
Tax distributions	(1,045)																(1,045)
Accumulated Other Comprehensive Income	90														90
Equity based compensation (in shares)											911,000	1,047,000
Equity based compensation	4,874										$ 10	$ 4,864
Net loss	(15,490)															(26)	(15,464)
Other comprehensive income (loss)	102
Net Income attributable to Legacy AON Shareholders	(15,489)
Ending balance (in shares) at Sep. 30, 2023					9,453,604	25,109,551	6,614,000	25,110,000
Ending balance (in units) at Sep. 30, 2023		0	0	0							0
Ending balance at Sep. 30, 2023	$ (341,223)						$ 1	$ 3						0	21	108	(341,356)
Redeemable Preferred Stock
Reverse Recapitalization, net (in shares)	152,000
Reverse Recapitalization, net	$ 2,089
Ending Balance (in shares) at Sep. 30, 2023	6,652,000
Ending Balance at Sep. 30, 2023	$ 64,986
Increase (Decrease) In Noncontrolling Interest [Roll Forward]
Reverse Recapitalization, net	36,873
Other comprehensive loss attributable to noncontrolling interests	9
Net loss attributable to noncontrolling interest	(11,924)
Fair value adjustment to redeemable noncontrolling interest	344,371
Ending Balance at Sep. 30, 2023	369,329
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reverse Recapitalization, net (in shares)							6,614,000	25,110,000	(19,495,000)	(3,000,000)	(5,615,000)	(1,047,000)
Reverse Recapitalization, net	(35,429)						$ 1	$ 3	$ (7,725)	$ (38,225)	$ (90)	$ (4,864)		17,602	(42)		(2,089)
Other comprehensive income (loss)	2														2
Net income (loss) before noncontrolling interest	(1,792)																(1,792)
Fair value adjustment to redeemable noncontrolling interest	(344,371)													(17,602)			(326,769)
Ending balance (in shares) at Sep. 30, 2023					9,453,604	25,109,551	6,614,000	25,110,000
Ending balance (in units) at Sep. 30, 2023		0	0	0							0
Ending balance at Sep. 30, 2023	$ (341,223)						$ 1	$ 3						$ 0	$ 21	$ 108	$ (341,356)

Accrued Other (FY) (Tables)

12 Months Ended

Dec. 31, 2022

Accrued Other [Abstract]

Accrued Other

Accrued other consisted of the following at December 31, 2022 and 2021:

	As of December 31,
	2022	2021
Refund liability	$14,544	$8,306
Deferred social security taxes – COVID	378	378
Current portion of finance lease liability	425	—
Other	2,453	5,108
Total accrued other	$17,800	$13,792

CONSOLIDATED STATEMENTS OF CASH FLOWS (FY) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2022

Dec. 31, 2021

Dec. 31, 2020

Cash flows from operating activities

Net income (loss)

$ 2,589

$ (105)

$ 21,951

Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities

Depreciation and amortization

6,719

6,079

3,656

Amortization of debt issuance costs

627

363

Amortization of right-of-use assets

^[1]

10,364

Loss on extinguishment of debt financing costs

Equity-based compensation

Deferred income taxes

786

(1,178)

Gain on sale of equipment

(121)

(79)

Deferred rent

1,293

651

Changes in operating assets and liabilities:

(24,873)

(30,803)

(35,485)

^[2]

(1,947)

(10,260)

(6,272)

607

(1,883)

(481)

(3,123)

(8,095)

(6,121)

(1,748)

(1,021)

(550)

^[3]

14,077

21,679

34,000

(1,435)

2,093

3,840

Operating lease liability

4,008

5,568

5,271

^[4]

(10,485)

(3,742)

(13,447)

17,189

Net cash (used in) provided by operating activities

1,699

1,394

735

(6,784)

(26,338)

37,245

Cash flows from investing activities

Purchases of property and equipment

(7,193)

(8,322)

(12,221)

Disposals of property and equipment

2,084

683

Purchase of marketable securities

(12,619)

Proceeds from sales of marketable securities

2,652

Acquisition of physician practices

(5)

(3,215)

(933)

Issuance of notes receivable - related parties

(243)

(1,263)

(5,478)

Collections on notes receivable - related parties

1,333

1,423

3,958

Net cash used in investing activities

(13,991)

(10,694)

(14,674)

Cash flows from financing activities

Repayments of revolving line of credit

(10,000)

(12,061)

Borrowings on long-term debt

16,250

65,000

12,518

Repayments of long-term debt

(27,098)

(12,522)

Issuance of class A-1 units, net of issuance costs

28,500

Cash paid for deferred offering costs

(206)

Repayments on finance and capital leases

(426)

(205)

Cash paid for debt financing costs

(271)

(1,153)

(177)

Net cash provided by financing activities

15,347

26,544

16,258

Net (decrease) increase in cash and cash equivalents and restricted cash

(5,428)

(10,488)

38,829

Cash, cash equivalents and restricted cash

Cash and cash equivalents, Beginning of Period

32,354

42,842

4,013

Cash and cash equivalents, End of Period

26,926

32,354

42,842

Supplemental consolidated cash flow information

Cash paid for interest

2,184

1,378

1,097

Cash paid for income taxes

335

Supplemental noncash investing and financing activities

Changes in accounts payable for capital additions to property and equipment

623

890

302

Assumed capital lease liabilities in acquisition of physician practice

1,097

Reduction of notes receivable as consideration for purchase of physician practice assets

654

Note payable for acquisition of physician practice

621

Payables for deferred offering costs

133

Disposal of property and equipment in exchange for reduction in finance lease liability

$ 72

$ 0

[1]	Includes related party amortization of operating right-of-use assets of $2,059 for the year ended December 31, 2022
[2]	Includes changes in related party balances of ($1,850), ($11,848) , and ($6,322) for the years ended December 31, 2022, 2021, and 2020, respectively
[3]	Includes changes in related party balances of $13,314, $23,309, and $37,744 for the years ended December 31, 2022, 2021 and 2020, respectively
[4]	Includes changes in related party balance of ($1,995) for the year ended December 31, 2022

Supplemental Condensed Balance Sheet Information - Schedule of Property and Equipment, net (Q3) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 59,552	$ 49,328
Accumulated depreciation and amortization	(23,312)	(17,348)
Property and equipment, net	36,240	31,980
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	30,078	26,076
Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,722	2,669
Medical equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	12,659	11,003
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,325	3,115
Signs
Property, Plant and Equipment [Line Items]
Property and equipment, gross	147	129
Automobiles
Property, Plant and Equipment [Line Items]
Property and equipment, gross	59	69
Software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4,412	4,834
Construction-in-progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 6,150	$ 1,433

Reverse Recapitalization (FY)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Reverse Recapitalization [Abstract]

Reverse Recapitalization

3. Reverse Recapitalization

The following table provides the historical cost of assets and liabilities of AON Inc. as of September 20, 2023.

			As of September 30, 2023
Cash and Cash Equivalents			$1,493
Current Liabilities			(13,295)
Long Term Liabilities			(6,791)
Total Net Liabilities			$(18,593)

2. Reverse Recapitalization

Business Combination Agreement

Reverse Recapitalization

Equity - Narrative (Q3) (Details) - USD ($) $ / shares in Units, $ in Thousands					2 Months Ended	3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 21, 2023	Sep. 20, 2023	Jun. 07, 2023	Mar. 04, 2020	Jul. 31, 2023	Sep. 30, 2023	Sep. 20, 2023	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2020	Jun. 30, 2023	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Invested capital contributions						$ 65,000		$ 65,000
Accrued dividend rate (in percent)								8.00%
Shares issued (in shares)										$ 28,500
Common Class A
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common unit, units outstanding (in units)						0		0	19,495,376		19,495,376	19,495,376	19,495,376	19,495,376
Accrued dividend rate (in percent)				8.00%
Class A and A-1 preferred returns and tax distributions			$ 4,000
Common stock, shares issued (in shares)		718,549	439,176				718,549
Common Class A-1
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common unit, units outstanding (in units)						0		0	1,842,520		2,281,696	1,842,520	1,842,520	1,842,520
Shares issued (in shares)	284		174
Accrued dividend rate (in percent)				4.00%
Class A and A-1 preferred returns and tax distributions			$ 4,100
Shares issued (in shares)		$ 7,200	$ 2,500				$ 9,700
Common Class B
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common unit, units outstanding (in units)						0		0	4,703,628		4,703,628	4,703,628	4,703,628	4,703,628
Class B-1
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock compensation expense						$ 4,900
Grants in period (in units)					415
Class C
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Temporary equity, redeemable period								5 years
Option to purchase additional units (in shares)			378
Purchase price of additional units (in dollars per share)			$ 26,423
Anti-dilution feature at fair value											$ 1,400
Stockholders
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of days after five year anniversary								30 days
AON Inc.
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stockholders' equity, conversion, threshold volume weighted average price period								30 days
Stockholders' equity, conversion, threshold stock price (in dollars per share) (less than) (greater than)								$ 16
AON LLC
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Issuance of units (in units)						34,724,025		34,724,025
Anti-Dilution Feature
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Changes in fair value adjustments of warrants and derivative liabilities						$ 4,700		$ 9,800
Option Feature
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Changes in fair value adjustments of warrants and derivative liabilities						$ (1,400)
AON LLC \| Common Class A
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common unit authorized (in units)									19,495,376
Issuance of units (in units)									19,495,376
Common unit, units outstanding (in units)									19,495,376
AON LLC \| Common Class A-1
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common unit authorized (in units)									3,000,245
Issuance of units (in units)									1,842,520
Common unit, units outstanding (in units)									1,842,520
AON LLC \| Common Class B
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Issuance of units (in units)									5,614,176
Units vested (in units)									4,703,628
Units vested upon consummation of business combination (in units)									910,548
Stock compensation expense									$ 100
Common Class A
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common unit, units outstanding (in units)									19,495,376					19,495,376
Shares issued (in shares)		1,047,343
Stockholders' equity, conversion, threshold volume weighted average price period								5 days
Common stock, shares issued (in shares)						9,453,604		9,453,604
Series A Preferred Stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Class A-1 distribution (in shares)		151,610
Stock price (in usd per share)						$ 10		$ 10
Series A Preferred Stock \| Stockholders
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stockholders' equity, conversion, threshold volume weighted average price period								30 days
Stockholders' equity, conversion, threshold stock price (in dollars per share) (less than) (greater than)								$ 10
Threshold stock price, conversion price adjustment (in usd per share)								$ 5
Series A Preferred Stock \| AEA Growth Management LP
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares issued (in shares)		6,651,610
Series A Preferred Stock \| Dividends Paid, Event Prior to June 7, 2024
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Accrued dividend rate (in percent)								125.00%
Series A Preferred Stock \| Dividends Paid, Event Prior to June 7, 2025, After June 7, 2024
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Accrued dividend rate (in percent)								120.00%
Series A Preferred Stock \| Dividends Paid, Event Prior to June 7, 2026, After June 7, 2025
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Accrued dividend rate (in percent)								115.00%
Series A Preferred Stock \| Dividends Paid, Event Prior to June 7, 2027, After June 7, 2026
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Accrued dividend rate (in percent)								110.00%
Series A Preferred Stock \| Dividends Paid, Event Prior to June 7, 2028, After June 7, 2027
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Accrued dividend rate (in percent)								105.00%
Series A Preferred Stock \| Dividends Paid, Event After June 7, 2028
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Accrued dividend rate (in percent)								100.00%

Supplemental Condensed Balance Sheet Information - Schedule of Inventory (Q3) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Inventory [Line Items]
Inventories	$ 37,844	$ 36,476	$ 34,529
Intravenous drugs
Inventory [Line Items]
Inventories	27,508	25,674	28,897
Oral pharmaceuticals
Inventory [Line Items]
Inventories	$ 10,336	$ 10,802	$ 5,632

Professional Liability Insurance (FY)	12 Months Ended
Professional Liability Insurance (FY)	Dec. 31, 2022
Professional Liability Insurance [Abstract]
Professional Liability Insurance	17. Professional Liability Insurance The Company has purchased claims-made professional liability insurance coverage through December 31, 2022 and 2021, covering up to $1.0 million per incident and $1.0 million in annual aggregate for each physician and covering up to $2.0 million per incident and $4.0 million in the aggregate at the entity level. The policy does not require a deductible per incident. As of December 31, 2022 and 2021, the gross malpractice insurance recovery balance was $2.2 million and $1.0 million, respectively, and the malpractice insurance reserve liability balance totaled $3.7 million and $2.2 million, respectively. The Company has a net tail liability of approximately $1.6 million and $1.1 million, respectively, for claims arising from incidents prior to December 31, 2022 and 2021 that are not yet reported as of December 31, 2022 and 2021.

Business Combinations, 2022 Acquisitions (FY) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Northern Arizona Hematology and Oncology [Member] \| Maximum [Member]
Asset Acquisitions [Abstract]
Aggregate purchase price	$ 0.1

Condensed Consolidated Statements of Operations and Comprehensive Loss (Q3) - USD ($)

3 Months Ended

9 Months Ended

Sep. 30, 2023

Sep. 30, 2022

Sep. 30, 2023

Sep. 30, 2022

Revenue

Total revenue

$ 336,305,000

$ 297,324,000

$ 955,003,000

$ 849,272,000

Costs and expenses

^[1]

310,894,000

267,647,000

880,827,000

780,658,000

Income (Loss) from operations

25,199,000

23,432,000

72,831,000

^[2]

66,155,000

^[2]

Transaction expenses

24,603,000

^[2]

151,000

^[2]

29,886,000

151,000

Total costs and expenses

360,696,000

291,230,000

983,544,000

846,964,000

(24,391,000)

6,094,000

(28,541,000)

2,308,000

Other income (expense)

Interest expense

(1,532,000)

(924,000)

(4,500,000)

(2,034,000)

Interest income

373,000

49,000

499,000

104,000

Other (expense) income, net

(3,309,000)

388,000

(7,689,000)

849,000

Income (loss) before income taxes, equity loss in affiliate, and noncontrolling interest

(28,859,000)

5,607,000

(40,231,000)

1,227,000

Income tax expense

315,000

Income (loss) before equity loss in affiliate and noncontrolling interest

(29,174,000)

5,607,000

(40,546,000)

1,227,000

Equity in loss of affiliate

(31,000)

(251,000)

Net income (loss) before noncontrolling interest

(29,205,000)

5,607,000

(40,797,000)

1,227,000

Net income (loss) and noncontrolling interest attributable to Legacy AON Shareholders prior to the reverse recapitalization

(15,489,000)

5,607,000

(27,081,000)

1,227,000

Net loss attributable to noncontrolling interest

(11,924,000)

Net loss attributable to Class A Common Stockholders, Diluted

(1,792,000)

Net loss attributable to Class A Common Stockholders, Basic

$ (1,792,000)

$ 0

$ (1,792,000)

$ 0

Loss per share of Class A Common Stock:

Earnings (loss) per unit, basic (in usd per share)

$ (0.61)

$ 0

$ (0.61)

$ 0

Earnings (loss) per unit, diluted (in usd per share)

$ (0.61)

$ 0

$ (0.61)

$ 0

Weighted average shares of Class A Common Stock Outstanding:

Weighted average shares for basic loss per share (in shares)

6,614,229

Diluted weighted average common units outstanding (in shares)

6,614,229

Other comprehensive income (loss):

Unrealized gains (losses) on marketable securities

$ 102,000

$ (77,000)

$ 190,000

$ (161,000)

Other comprehensive gain (loss)

102,000

(77,000)

190,000

(161,000)

Comprehensive income (loss)

(29,103,000)

5,530,000

(40,607,000)

1,066,000

Other comprehensive income (loss) attributable to Legacy AON Shareholders

(15,398,000)

5,530,000

(26,902,000)

1,066,000

Other comprehensive loss attributable to noncontrolling interests

(11,915,000)

Comprehensive Income (Loss), Net Of Tax, Attributable To Common Stockholders

(1,790,000)

Patient service revenue, net

Revenue

Total revenue

332,195,000

293,612,000

945,681,000

840,507,000

Other revenue

Revenue

Total revenue

$ 4,110,000

$ 3,712,000

$ 9,322,000

$ 8,765,000

[1]	Includes related party inventory expense of $271,790 and $236,077 and $777,478 and $682,671 for the three and nine months ended September 30, 2023 and 2022, respectively.
[2]	Includes related party rent of $679 and $655 and $2,037 and $2,037 for the three and nine months ended September 30, 2023 and 2022, respectively.

Leases - Maturities of Operating and Financing Lease Liabilities (Q3) (Details) - USD ($)
$ in Thousands

Sep. 30, 2023

Dec. 31, 2022

Dec. 31, 2021

Operating Lease

2023 (remainder of year after September 30, 2023)

$ 1,679

10,940

$ 11,215

9,830

10,049

9,413

7,762

8,194

7,448

24,154

64,210

54,069

(14,826)

(7,668)

49,384

46,401

Long-term lease liabilities, net of current portion

(7,123)

^[1]

(9,177)

^[1],[2]

$ 0

^[2]

42,261

^[3]

37,224

^[3],[4]

^[4]

Finance Leases

2023 (remainder of year after September 30, 2023)

188

753

491

731

491

492

469

428

231

528

3,120

2,277

(364)

(233)

2,756

2,044

Long-term lease liabilities, net of current portion

(630)

(425)

$ 0

$ 2,126

$ 1,619

[1]	Includes related party current portion of operating lease liabilities of $1,912 and $1,836 at September 30, 2023 and December 31, 2022, respectively
[2]	Includes related party current portion of operating lease liabilities of $1,836 at December 31, 2022
[3]	Includes related party long-term operating lease liabilities of $9,994 and $11,631 at September 30, 2023 and December 31, 2022, respectively
[4]	Includes related party long-term operating lease liabilities of $11,631 at December 31, 2022

Income Taxes (FY) (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
Income Taxes (FY) (Details) - USD ($)	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current [Abstract]
Federal					$ 0	$ (306,000)	$ 152,000
State					0	(20,000)	123,000
Current income tax expense (benefit)					0	(326,000)	275,000
Deferred [Abstract]
Federal					0	433,000	(922,000)
State					0	353,000	(136,000)
Deferred income tax expense (benefit)					0	786,000	(1,058,000)
Total income tax expense (benefit)	$ 315,000	$ 0	$ 315,000	$ 0	$ 0	$ 460,000	$ (783,000)
Reconciliation of Effective Income Tax Rate [Abstract]
Federal statutory income tax rate					21.00%	21.00%	21.00%
State taxes, net of federal benefit					(11.94%)	(97.95%)	(0.80%)
State rate change					(2.15%)	(3.41%)	0.07%
Other					(3.71%)	3.00%	0.07%
Nontaxable passthrough LLC income					(87.14%)	(658.26%)	(27.31%)
Increase in valuation allowance					83.94%	864.95%	3.26%
Effective tax rate	(1.10%)	0.00%	(0.80%)	0.00%	0.00%	129.33%	(3.71%)
Deferred tax assets [Abstract]
Net operating loss carryforwards					$ 6,589,000	$ 5,166,000
Accrued expenses					165,000	426,000
Deferred tax assets					6,754,000	5,592,000
Valuation allowance					(5,835,000)	(3,662,000)
Net deferred tax asset					919,000	1,930,000
Deferred tax liabilities [Abstract]
Prepaid expenses					0	64,000
Accounting method change					918,000	1,866,000
Fixed assets					1,000	0
Deferred tax liabilities					919,000	1,930,000
Net deferred tax asset					0	0
Operating Loss Carryforwards [Abstract]
Federal net operating loss carryforwards					25,400,000	20,100,000
State net operation loss carryforwards					26,800,000	20,500,000
Increase in valuation allowance					2,200,000	3,000,000
Uncertain Tax Positions [Abstract]
Uncertain tax positions					0	0
Interest and penalties recognized for uncertain tax positions					0	0	$ 0
Accrued interest and penalties recognized for uncertain tax positions					$ 0	$ 0

Income Taxes (FY) (Tables)

12 Months Ended

Dec. 31, 2022

Income Taxes [Abstract]

Income Tax Expense (Benefit)

The income tax expense (benefit) in 2022, 2021, and 2020 consisted of the following:

	Year Ended December 31,
	2022	2021	2020
Current
Federal	$—	$(306)	$152
State	—	(20)	123
	—	(326)	275
Deferred
Federal	—	433	(922)
State	—	353	(136)
	—	786	(1,058)
Total income tax expense (benefit)	$—	$460	$(783)

Reconciliation of Statutory to Effective Income Tax Rate

The differences between the federal tax rate and the Company’s effective tax rate for the years ended December 31, 2022, 2021, and 2020 are as follows:

	Year Ended December 31,
	2022	2021	2020
Federal statutory income tax rate	21.00%	21.00%	21.00%
State taxes, net of federal benefit	(11.94)	(97.95)	(0.80)
State rate change	(2.15)	(3.41)	0.07
Other	(3.71)	3.00	0.07
Nontaxable passthrough LLC income	(87.14)	(658.26)	(27.31)
Increase in valuation allowance	83.94	864.95	3.26
Effective tax rate	—%	129.33%	(3.71)%

Deferred Tax Assets and Liabilities

Components of the net deferred tax assets and liabilities at December 31, 2022 and 2021 are as follows:

	As of December 31,
	2022	2021
Deferred tax assets
Net operating loss carryforwards	$6,589	$5,166
Accrued expenses	165	426
Deferred tax assets	6,754	5,592
Valuation allowance	(5,835)	(3,662)
Net deferred tax asset	919	1,930
Deferred tax liabilities
Prepaid expenses	—	64
Accounting method change	918	1,866
Fixed assets	1	—
Deferred tax liabilities	919	1,930
Net deferred tax asset	$—	$—

Supplemental Condensed Balance Sheet Information - Schedule of Accrued Other (Q3) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Business [Abstract]
Refund liability	$ 14,521	$ 14,544	$ 8,306
Deferred social security taxes - COVID	0	378	378
Excise taxes payable	2,700	0
Less: current portion of lease liabilities	630	425	0
Other	5,126	2,453
Total accrued other	$ 22,977	$ 17,800	$ 13,792
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Total accrued other	Total accrued other

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (FY) - USD ($) $ in Thousands	Common Stock [Member] Class A Units [Member]	Common Stock [Member] Class A-1 Units [Member]	Common Stock [Member] Class B Units [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]	Total
Beginning balance at Dec. 31, 2019	$ 7,725	$ 0	$ 40	$ 0	$ 1,393	$ 9,158
Beginning balance (in units) at Dec. 31, 2019	19,495	0	3,218
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A-1 units, net of issuance costs		$ 28,500				28,500
Issuance of Class A-1 units, net of issuance costs (in units)		1,843
Net income	$ 0	$ 0	$ 0	0	21,951	21,951
Other comprehensive loss						0
Equity-based compensation	0	0	20	0	0	20
Ending balance at Dec. 31, 2020	$ 7,725	$ 28,500	$ 60	0	23,344	59,629
Ending balance (in units) at Dec. 31, 2020	19,495	1,843	3,218
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 0	$ 0	$ 0	0	(105)	(105)
Other comprehensive loss						0
Equity-based compensation	0	0	$ 20	0	0	20
Equity based compensation (in shares)			1,485
Ending balance at Dec. 31, 2021	$ 7,725	$ 28,500	$ 80	0	23,239	59,544
Ending balance (in units) at Dec. 31, 2021	19,495	1,843	4,704
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive loss						(161)
Ending balance at Sep. 30, 2022				(161)	24,466	60,625
Beginning balance at Dec. 31, 2021	$ 7,725	$ 28,500	$ 80	0	23,239	59,544
Beginning balance (in units) at Dec. 31, 2021	19,495	1,843	4,704
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 0	$ 0	$ 0	0	2,589	2,589
Other comprehensive loss	0	0	0	(117)	0	(117)
Ending balance at Dec. 31, 2022	$ 7,725	$ 28,500	$ 80	(117)	25,828	62,016
Ending balance (in units) at Dec. 31, 2022	19,495	1,843	4,704
Beginning balance at Jun. 30, 2022				(84)	18,859	55,090
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive loss						(77)
Ending balance at Sep. 30, 2022				$ (161)	$ 24,466	$ 60,625

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481687/323-10-50-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 28
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482907/825-10-50-28

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482765/220-10-50-6

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-3

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480175/815-40-65-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

Property and Equipment, Net [Abstract]

Summary of Significant Accounting Policies and Basis of Presentation, Goodwill (FY) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Goodwill [Abstract]
Impairment of goodwill	$ 0

Reverse Capitalization - Schedule of Historical Cost (Q3) (Details) $ in Thousands	Sep. 30, 2023 USD ($)
Reverse Recapitalization [Abstract]
Cash and cash equivalents	$ 1,493
Current Liabilities	(13,295)
Long Term Liabilities	(6,791)
Total Net Liabilities	$ (18,593)

Property and Equipment, Net (FY)

12 Months Ended

Dec. 31, 2022

Property and Equipment, Net

9. Property and Equipment, Net

Property and equipment, net, consisted of the following at December 31, 2022 and 2021:

	As of December 31,
	2022	2021
Leasehold improvements	$26,076	$23,744
Furniture, fixtures and equipment	2,669	2,346
Medical equipment	11,003	8,811
Computer equipment	3,115	2,713
Signs	129	117
Automobiles	69	69
Software	4,834	4,036
Construction-in-progress	1,433	1,445
	49,328	43,281
Accumulated depreciation and amortization	(17,348)	(10,633)
Property and equipment, net	$31,980	$32,648

For the years ended December 31, 2022, 2021 and 2020, depreciation expense was approximately $6.7 million, $6.1 million, and $3.7 million, respectively, and is included in general and administrative expenses in the Consolidated Statements of Operations and Comprehensive Income (Loss).

Construction-in-progress consists primarily of capital expenditures on new physician practice facilities which have not yet been opened and improvements to existing practice facilities which are not complete at year-end.

Reverse Capitalization - Narrative (Q3) (Details)
$ in Thousands

3 Months Ended

9 Months Ended

Sep. 30, 2023

USD ($)

person

Sep. 20, 2023

USD ($)

Sep. 30, 2023

USD ($)

person

Sep. 30, 2022

USD ($)

^[1]

Sep. 30, 2023

USD ($)

person

Sep. 30, 2022

USD ($)

Gain (Loss) On Reverse Recapitalization

$ 18,200

Transaction expenses

$ 13,000

$ 24,603

^[1]

$ 151

$ 29,886

$ 151

Public and Private Warrants

Gain (loss) on issuance of warrants

$ (5,200)

Fair Value Adjustment of Warrants

$ 4,300

AON Inc.

Number of board of managers designated by company | person

AON Common Unit

Number of board of managers designated by majority common unit holders | person

[1]	Includes related party rent of $679 and $655 and $2,037 and $2,037 for the three and nine months ended September 30, 2023 and 2022, respectively.

Equity (Q3)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Stockholders' Equity [Abstract]

Equity

12. Equity

Prior Period Presentation

For periods prior to the Reverse Recapitalization, AON LLC had equity and stock-based compensation described below authorized, issued and outstanding. As discussed in Note 1, upon the Closing of the Business Combination, Legacy AON Shareholders received Class A Common Stock, Class B Common Stock, or Class B Prefunded Warrants and AON LLC reclassified their existing Class A, Class A-1, and Class B Units into AON LLC Common Units, pursuant to the terms of the Business Combination Agreement.

The Company recasted Historical AON LLC Equity outstanding for the periods prior to the Reverse Recapitalization, equal to the Per Company Unit Exchange Ratio, pursuant to the Business Combination, that was applied to the Class A, Class A-1, and Class B Units. The historical AON LLC units disclosed in this note give effect to the conversion for all periods presented, as follows.

Class A Units

AON LLC had authorized 19,495,376 units of Class A Units, of which 19,495,376 units were issued and were outstanding as of December 31, 2022.

Class A-1 Units

AON LLC had authorized 3,000,245 units of Class A-1 Units, of which 1,842,520 units were issued and were outstanding as of December 31, 2022.

Class B Units (Profit Interest)

The Class B units were issued through the 2017 Profits Interest Plan adopted by the Company in October 2017. The Class B Units represented a non-voting equity interest in AON LLC that entitled the holder to appreciation in the equity value of AON LLC arising after the date of grant and after such time as an applicable hurdle amount is met. AON LLC recognized the cost of services received in exchange for Class B Units based on the grant-date fair value. That cost was recognized over the period during which the service provider is required to provide service in exchange for the award over the requisite service period or based on performance. AON LLC used the Black-Scholes-Merton pricing model to estimate the fair value of profits interest unit awards. On an as converted basis, as of December 31, 2022, AON LLC issued 5,614,176 Class B Units, of which 4,703,628 were vested and outstanding; the remaining 910,548 of Class B units vested upon consummation of the Business Combination. The stock compensation expense that was recognized for the vesting of the Class B Units was less than $0.1 million.

The following table summarizes the changes to AON LLC’s Class A, Class A-1, and Class B Units for the three and nine months ended September 30, 2023, and 2022.

in thousands, except for share and per share amounts	Three Months Ended September 30,		Nine Months Ended September 30,
	2023	2022	2023	2022
Class A Units, value
Beginning of Period	$7,725	$7,725	$7,725	$7,725
Issuance of Units	—	—	—	—
Impact of the Reverse Recapitalization	(7,725)	—	(7,725)	—
End of Period	$—	$7,725	$—	$7,725
Class A Units, units
Beginning of Period	19,495,376	19,495,376	19,495,376	19,495,376
Issuance of Units	—	—	—	—
Impact of the Reverse Recapitalization	(19,495,376)	—	(19,495,376)	—
End of Period	—	19,495,376	—	19,495,376

in thousands, except for share and per share amounts	Three Months Ended September 30,		Nine Months Ended September 30,
	2023	2022	2023	2022
Class A-1 Units, value
Beginning of Period	$31,040	$28,500	$28,500	$28,500
Issuance of Units	7,185	—	9,725	—
Impact of the Reverse Recapitalization	(38,225)	—	(38,225)	—
End of Period	$—	$28,500	$—	$28,500
Class A-1 Units, units
Beginning of Period	2,281,696	1,842,520	1,842,520	1,842,520
Issuance of Units	718,549		1,157,725
Impact of the Reverse Recapitalization	(3,000,245)		(3,000,245)
End of Period	—	1,842,520	—	1,842,520

in thousands, except for share and per share amounts	Three Months Ended September 30,		Nine Months Ended September 30,
	2023	2022	2023	2022
Class B Units, value
Beginning of Period	$80	$90	$80	$80
Equity based compensation	10	5	10	15
Impact of the Reverse Recapitalization	(90)	—	(90)
End of Period	$—	$95	$—	$95
Class B Units, units
Beginning of Period	4,703,628	4,703,628	4,703,628	4,703,628
Units Vested	910,548	—	910,548	—
Impact of the Reverse Recapitalization	(5,614,176)	—	(5,614,176)	—
End of Period	—	4,703,628	—	4,703,628

Class B-1 Units

In June and July of 2023, the Company granted a total of 415 AON LLC Class B-1 Units to certain employees under the 2017 Profits Interest Plan (the “Plan”). The Class B-1 Units vested upon the consummation of the Business Combination, therefore, $4.9 million of expense has been recognized in the condensed consolidated statement of operations and comprehensive loss for the three months ended September 30, 2023. Upon the closing of the Business Combination, the vested Class B-1 Units were reclassified to AON LLC Common Units and exchanged for newly issued shares of Class A Common Stock equal to the Per Company Unit Exchange Ratio, pursuant to the Business Combination Agreement, which resulted in the issuance of 1,047,343 shares of New AON Class A Common Stock.

Mezzanine Equity Class C Units

As described in Note 1, the AON LLC Class C Units were converted into AON LLC Series A Preferred Units as of the Closing Date. Concurrently, New AON issued a number of shares of New AON Series A Preferred Stock equal to the number of AON LLC Series A Preferred Units held by the AON Class C Preferred Investor to AEA Growth Management LP, the parent of AON Class C Preferred Investor (“AEA Growth”) in exchange for all the shares of common stock held by AEA Growth in the AON Class C Preferred Investor. Promptly after the First Step, the AON Class C Preferred Investor merged with and into New AON whereby the separate existence of the AON Class C Preferred Investor ceased and New AON held all the AON LLC Series A Preferred Units. On an as converted basis, as of September 20, 2023, 6,651,610 Series A Preferred Stock were issued to AEA Growth Management LP.

The AON LLC Class C Units were contingently redeemable convertible preferred units and classified as mezzanine equity on the condensed consolidated balance sheet as of June 30, 2023 because the units were redeemable five years from the issuance date, at the option of the holder. As of June 30, 2023, the AON LLC Class C Units were recorded at their initial carrying value, net of offering costs. The Class C Units were not being accreted to redemption value, as the redemption was not probable due to the removal of the redemption right pursuant to the Business Combination. See discussion below.

The Class C Units had materially the same rights as the Series A Preferred Stock issued by the Company to AEA Growth Management LP, the parent of the AON Class C Preferred Investor, with the exception of the “AON LLC Class C Unit Redemption Right” and the “Class C Option to Purchase Additional Shares”, discussed below. Further, the Class C Units did not contain a mandatory conversion feature that allowed AON LLC to force the Class C Investor to convert the Class C Units into another equity unit in AON LLC and the Class C Units did not have a one time conversion price adjustment.

Class C Unit Redemption Right

After the fifth anniversary of the Effective Date (June 7, 2028), the holders of a majority of the Class C Units had the right to cause the Company to redeem all of the Class C Units. The redemption price per Class C Unit was equal to the greater of (i) the Class C Liquidation Preference and (ii) the Fair Market Value of a Class C Unit (the “Class C Redemption Price”). The Class C Liquidation Preference is defined as an amount equal to the sum of (a) the Class C Preferred Return of such Class C Member and (b) the amount of such Class C Member’s Net Invested Capital Contributions of $65.0 million. The Class C Unit Preferred Return is defined as the cumulative, semiannually-compounded return of 8% per annum based on the original Net Invested Capital Contributions of $65.0 million. The Class C Unit Redemption Right was removed as of the Closing of the Business Combination.

Class C Unit Option to Purchase Additional Units

In accordance with the terms of the Amended and Restated Class C Convertible Preferred Unit Purchase Agreement dated June 7, 2023, the Class C Preferred Investor had an option to purchase an additional 378 AON Class C Units until the Closing of the Business Combination at a purchase price of $26,423 per Unit (“Option Feature”). The Company determined that this Option Feature was required to be accounted for as a derivative in accordance with ASC 815. The fair value of the derivative was estimated to be $1.4 million as of June 30, 2023. The Class C Preferred Investor did not exercise this option prior to the Closing of the Business Combination. As a result, the Company recognized a gain of $1.4 million in other (expense) income, net in the condensed consolidated statements of operations and comprehensive loss for the three months ended September 30, 2023. The Class C Unit Option expired as of the Closing of the Business Combination.

Series A Preferred Stock (Mezzanine Equity)

New AON Series A Preferred Stock is redeemable for cash or the value of the property, rights or securities to be paid or distributed in the event of a Deemed Liquidation Event (which outside of the Company’s control). As a result, the Company has determined that the New AON Series A Preferred Stock should be classified as mezzanine equity. At the closing of the Business Combination, the Company exchanged existing AON LLC Class C Units for Series A Preferred Stock in the Company. Based on the qualitative changes to the instrument, this exchange is considered an extinguishment for accounting purposes, with the Company recording a deemed dividend of $2.1 million to account for the difference between the carrying value of the Class C Units and the fair value of the Series A Preferred Stock at the transaction date. This amount is reflected in the condensed consolidated statements of mezzanine and stockholders’ equity as part of the reverse recapitalization, net. See further discussion on the PIK Dividend discussed below.

The Series A Preferred Stock are not being accreted to redemption value, as the Series A Preferred Stock are not redeemable, nor are they probable of becoming redeemable.

Dividends

The Series A Preferred Stock accrue dividends at a cumulative, semiannually-compounded return of 8% per annum based on the original Net Invested Capital Contributions from the Class C Units of $65.0 million. These dividends may be paid in cash or accumulate into the Accrued Value at the option of New AON. The accrual shall be calculated on June 30 and December 31 and with respect to the semiannually-compounded return, no interest is required to be paid on any present or future Series A Preferred Stock accrued dividends. The Series A Preferred Stock also participate in distributions with the Class A Common stockholders.

On September 20, 2023, the Company issued 6,651,610 Series A Preferred Stock to AEA Growth Management LP. The number of Series A Preferred Stock shares issued at the Closing of the Business Combination was equal to the aggregate Class C Liquidation Preference pursuant to the Business Combination Agreement. As a result, the

issuance of the Series A Preferred Stock effectively included an in-kind payout (“PIK”) of the accrued dividend since the calculation of the amount issued was based on the Class C Liquidation Preference. As of the Closing, the Company recorded a dividend of 151,610 Series A Preferred Stock PIK shares with respect to the accrued dividends on the Series A Preferred Stock (the “PIK Dividend”).

Voting

The holders of the Preferred Stock are entitled to elect and appoint one of the directors (“Series A Director”) to the Board of Directors. All other directors are appointed by the Class A and Class B Common stockholders. There are no restrictions on which matters the Series A Preferred stockholders are entitled to vote. The Series A Preferred stockholders are entitled to the number of votes equal to the number of shares of Common Stock into which the Series A Preferred Stock would be convertible on the record date of the vote.

Conversion Rights

The Series A Preferred Stock is convertible, at the option of the holder, at any time, and without the payment of additional consideration by the holder, into such number of fully-paid Class A Common Stock as is determined by dividing the Accrued Value by the Conversion Price in effect at the time of conversion (“Conversion Ratio”). The Accrued Value is the Original Issue Price (which is $10.00 per share of Preferred Stock, as adjusted for any stock split, stock dividend, combination, or other recapitalization) plus any unpaid dividends, compounded semi-annually. The Conversion Price is initially $10.00 per Preferred Share subject to adjustment for dilutive issuances of additional shares, dividends to common stockholders, stock splits, mergers, and a five-year anniversary special adjustment based on the volume weighted average price of the common stock. These dividends may be paid in cash or accumulate into the Accrued Value, at the option of New AON, on June 30 and December 31 of each year. The Conversion Rights shall terminate at the close of business on the day prior to the date of a Change of Control.

If at any time on or after the 30th day after the five-year anniversary of the issue date, any of the Series A Preferred Stock remain outstanding and the 30-Day VWAP of the Common Stock is less than $10.00 (as adjusted for any stock split, stock dividend, combination, or other recapitalization or reclassification), then the Conversion Price shall be adjusted to the greater of (x) the 30-Day VWAP on such date of determination and (y) $5.00 (as adjusted for any stock split, stock dividend, combination, or other recapitalization or reclassification).

New AON also has the right on or after the third-year anniversary of the date of issuance to cause all (but not less than all) of the outstanding shares of Series A Preferred Stock to be converted into shares of Class A Common Stock for each share of Series A Preferred Stock at the Conversion Ratio detailed above. The Company may only convert shares of Series A Preferred Stock into shares of Common Stock if the 30-Day VWAP of the Common Stock immediately prior to the Company Conversion Date is greater than $16.00 (as adjusted for any stock split, stock dividend, combination, or other recapitalization).

Liquidation Preferences

In the event of voluntary or involuntary liquidation, dissolution or winding up of the Company or an Initial Public Offering (IPO) or Exit Event, the Series A Preferred Stock have preferential liquidation rights. If a Deemed Liquidation Event were to occur, each Series A Preferred stockholder is entitled to be paid out of the assets of the Company available for distribution, equal to the greater of the following:

(i)	The Original Issue Price of $10 per Series A Preferred Stock multiplied by the Applicable Percentage plus any Accrued Dividends on such share of Series A Preferred Stock; or

(ii)	Such amount per share as would have been payable had all shares of Series A Preferred Stock been converted into Common Stock immediately prior to such Deemed Liquidation Event.

The Series A Preferred Stock Applicable Percentage is defined as a percentage equal to (a) one hundred twenty-five percent (125%) if an Exit Event, dissolution, liquidation, or winding-up occurs prior to June 7, 2024, (b) one hundred twenty percent (120%) if an Exit Event, dissolution, liquidation, or winding up occurs after June 7, 2024, but prior to June 7, 2025, (c) one hundred fifteen percent (115%) if an Exit Event, dissolution, liquidation, or winding-up occurs after June 7, 2025, but prior to June 7, 2026, (d) one hundred ten percent (110%) if an Exit Event, dissolution, liquidation, or winding up occurs after June 7, 2026, but prior to June 7, 2027, (e) one hundred five percent (105%) if an Exit Event, dissolution, liquidation, or winding-up occurs after June 7, 2027, but prior to June 7, 2028, (f) one hundred percent (100%) if an Exit Event, dissolution, liquidation, or winding-up occurs after June 7, 2028.

Distributions to Class A and Class A-1 Members

On March 4, 2020, the AON LLC entered into the Second Amended and Restated Limited Liability Agreement (“Second Operating Agreement”) which established another class of equity, Class A-1 Units. The Second Operating Agreement provided, among other things, that the Class A and A-1 Units would receive a cumulative, annually-compounded, preferred return of 8.0% and 4.0%, respectively, on capital contributions when and if distributions are declared by the Board of the Company.

Prior to the issuance of the Class C Units on June 7, 2023 as discussed above, the Class A and A-1 unitholders were paid a cash distribution of $4.0 million and $4.1 million, respectively, representing the cumulative accrued preferred return to June 7, 2023.

On June 7, 2023, in connection with the issuance of the Class C Units, AON LLC entered into the Third Amended and Restated Limited Liability Agreement (“Third Operating Agreement”) which, among other things, eliminated any provisions for future preferred returns on Class A and A-1 units.

Class A-1 Anti-Dilution Feature

Prior to the Closing, in the event AON LLC, prior to a Qualified IPO, issued additional membership equity (“Additional Issuance”) at a valuation that represents a purchase price that is less than the New Unit Purchase Price, as defined, AON LLC was obligated to issue additional Class A-1 Units, for no consideration, such that the Class A-1 unitholder maintains the same percentage ownership as prior to the Additional Issuance (“Anti-Dilution Feature”).

The Company determined that the Anti-Dilution Feature met the definition of a derivative in accordance with ASC 815. The total loss on derivatives for the three months and nine months ended September 30, 2023 relating to this feature is $4.7 million and $9.8 million, respectively, and was recorded in other (expense) income, net in the condensed consolidated statements of operations and comprehensive loss.

As a result of the Anti-Dilution Feature, upon the issuance of the Class C Units on June 7, 2023 and the Closing of the Business Combination on September 20, 2023, the Company issued an additional 174 and 284 Class A-1 Units, that were subsequently converted into 439,176 and 718,549 AON Common Units using the Per Company Unit Exchange Ratio, pursuant to the Business Combination Agreement. The total fair value of the issuance of additional Class A-1 shares on June 7, 2023 and September 20, 2023 was $2.5 million and $7.2 million, respectively, for a cumulative $9.7 million recorded as Class A-1 member equity in the condensed consolidated statements of mezzanine and stockholders’ equity. Upon the Closing of the Business Combination, the Class A-1 Anti-dilution Feature was eliminated and the derivative liability was fully extinguished.

12. Stockholders’ Equity

AON LLC had equity and stock-based compensation described below. The Company recasted Historical AON LLC Equity outstanding for the periods prior to the reverse recapitalization, equal to the Per Company Unit Exchange Ratio, pursuant to the Reverse Recapitalization, that was applied to the Class A, Class A-1, and Class B Units.

The economic interests of the members in AON LLC are represented by units consisting of Class A, Class A-1, and Class B membership units and AON LLC is authorized to issue an unlimited number of each class of units. The Amended and Restated Limited Liability Company Agreement (“Amended LLC Agreement”) dated October 20, 2017 specifies the members’ rights and obligations relating to contributions, distributions, allocation of income and loss and other matters.

Class A units

All Class A units are entitled to one vote per unit. The Class A units represent a percentage interest in AON LLC determined by subtracting all of the Class B units’ interests. However, the Class A units’ percentage shall not be less than 70%. There were 19,495,376 Class A units outstanding at December 31, 2022 and 2021 from an initial contribution of capital of $7.7 million.

Class A-1 units

In March 2020, AON LLC entered into the Second Amended and Restated Limited Liability Agreement (“Second Amended LLC Agreement”). The Second Amended LLC Agreement established another class of equity, Class A-1 units, of which 1,842,520 units were issued to the Class A-1 Member upon the contribution of capital of $30.0 million. The Class A-1 Member is an affiliate of AON LLC’s largest supplier of oncology products. The Class A-1 units have rights similar to Class A units including one vote per unit; however, the Second Amended LLC Agreement now provides for a cumulative, annually- compounded, unguaranteed, preferred return of 8.0% on Class A capital contributions and 4.0% on Class A-1 capital contributions. AON LLC paid an investment banking firm a

fee of $1.5 million in connection with the closing of this transaction. The $30.0 million capital contribution less brokerage fees of $1.5 million is included as a net capital contribution of $28.5 million in the Consolidated Statements of Members’ Equity and Consolidated Statements of Cash Flows.

Class B units

Class B units are issued through the 2017 Profits Interest Plan adopted by the Company in October 2017. The Class B units are available to be granted to certain employees to promote the long-term growth and profitability of the Company and represent profits interest awards. Awards vest over a two-to-five-year period based on anniversary date for certain employees and cliff vest on the fifth anniversary date for certain other employees. All awards vest immediately upon a change in control of the Company. All unvested awards expire upon a grantee’s termination of employment. A grantee has no ability to put the award back to the Company absent a distribution or liquidation event. Class B units have no voting rights.

In March 2020, the Company entered into the Second Amended LLC Agreement and in connection with the admission of the Class A-1 Member, the Company restructured the waterfall, and removed the 30% collar on the Class B Units. In order to effectuate these changes, the Company adopted the Second Amended LLC Agreement and a new capital table which, assigned new numbers of Class B units based on their percentage interest relative to the Class A Members by a factor of 101 units. The changes to the capital table were expressly called out and approved by the Class A Members and Class B Members in their Signature Pages and Joinders to the Second Amended LLC Agreement.

Aggregate equity-based compensation expense recorded for the years ended December 31, 2021 and 2020 related to the Class B units was $20 thousand and is reflected in the carrying value of the Class B Units on the Consolidated Balance Sheets as of December 31, 2022 and 2021. Compensation expense for the year ended December 31, 2022 and unrecognized compensation expense related to unvested units was not material. As of December 31, 2022 and 2021, 5,614,176 Class B Units were outstanding and 4,703,628 Class B Units were vested. No Class B Units were issued, vested or forfeited during the year ended December 31, 2022.

The entire disclosure for equity.

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Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities

CONSOLIDATED STATEMENTS OF CASH FLOWS (FY) (Parenthetical) - USD ($)
$ in Thousands

9 Months Ended

12 Months Ended

Sep. 30, 2023

Sep. 30, 2022

Dec. 31, 2022

Dec. 31, 2021

Dec. 31, 2020

Amortization of right-of-use assets

$ 6,194

^[1]

$ 7,766

^[1]

$ 10,364

^[2]

$ 0

^[2]

$ 0

^[2]

Changes in operating assets and liabilities:

(1,367)

^[3]

876

^[3]

(1,947)

^[4]

(10,260)

^[4]

(6,272)

^[4]

Operating lease liability

13,889

^[5]

9,586

^[5]

14,077

^[6]

21,679

^[6]

34,000

^[6]

(5,625)

^[7]

(8,252)

^[7]

(10,485)

^[8]

Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities

Amortization of right-of-use assets

1,601

1,536

2,059

Changes in operating assets and liabilities:

1,299

(832)

(1,850)

(11,848)

(6,322)

Operating lease liability

10,627

23,309

13,314

$ 23,309

$ 37,744

$ (1,835)

$ (1,446)

$ (1,995)

[1]	Includes related party amortization of operating right-of-use assets of $1,601 and $1,536 for the nine months ended September 30, 2023 and 2022, respectively.
[2]	Includes related party amortization of operating right-of-use assets of $2,059 for the year ended December 31, 2022
[3]	Includes changes in related party balances of ($1,299) and $832 for the nine months ended September 30, 2023 and 2022, respectively.
[4]	Includes changes in related party balances of ($1,850), ($11,848) , and ($6,322) for the years ended December 31, 2022, 2021, and 2020, respectively
[5]	Includes changes in related party balances of $10,627 and $23,309 for the nine months ended September 30, 2023 and 2022, respectively.
[6]	Includes changes in related party balances of $13,314, $23,309, and $37,744 for the years ended December 31, 2022, 2021 and 2020, respectively
[7]	Includes changes in related party balances of ($1,835) and ($1,446) for the nine months ended September 30, 2023 and 2022, respectively.
[8]	Includes changes in related party balance of ($1,995) for the year ended December 31, 2022

Basis of Presentation and Significant Accounting Policies (Q3)

9 Months Ended

Sep. 30, 2023

Basis of Presentation and Significant Accounting Policies

2. Basis of Presentation and Significant Accounting Policies

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements of the Company were prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and in accordance with the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations, although the Company believes that the disclosures are adequate to make the information presented not misleading. Management believes the unaudited condensed consolidated financial statements for the interim periods presented contain all necessary adjustments, of a normal recurring nature, to state fairly, in all material respects, the Company’s financial position, results of operations and cash flows for the interim periods presented. These condensed consolidated financial statements were prepared on the same basis as and should be read in conjunction with the Company’s annual consolidated financial statements. These unaudited condensed consolidated financial statements should be read in conjunction with such audited consolidated financial statements and related notes thereto of AON LLC and its wholly-owned subsidiaries, included in the proxy statement/prospectus of Digital Transformation Opportunities Corp., dated July 18, 2023 (the “Proxy Statement/Prospectus”). Operating results for the three and nine months ended September 30, 2023 are not necessarily indicative of the results the Company expects for the entire year.

For the three and nine months ended September 30, 2023, these unaudited condensed consolidated financial statements reflect the consolidated results of operations, comprehensive income (loss), cash flows and changes in equity of AON LLC and its wholly-owned subsidiaries for the period of January 1, 2023 through September 20, 2023, the Closing Date of the Reverse Recapitalization, and the consolidated results of operations, comprehensive income (loss), cash flows and changes in stockholders’ equity of AON Inc. and its consolidated subsidiaries, including AON LLC, for the period of September 21, 2023 through September 30, 2023. The condensed consolidated balance sheet at September 30, 2023 presents the financial condition of AON Inc. and its consolidated subsidiaries, including AON

LLC, and reflects the initial recording of the assets and liabilities of AON Inc. at their historical cost (see Note 3). All intercompany balances and transactions of AON LLC prior to the Reverse Recapitalization have been eliminated. All intercompany balances and transactions of AON Inc. after the Reverse Recapitalization have been eliminated.

For the three and nine months ended September 30, 2022, these unaudited condensed consolidated financial statements present the consolidated results of operations, comprehensive income (loss), cash flows and changes in equity of AON LLC. The condensed consolidated balance sheet as of December 31, 2022 presents the financial condition of AON LLC and its wholly-owned subsidiaries. All intercompany balances and transactions of AON LLC have been eliminated.

In accordance with Accounting Standards Codification (“ASC”) Topic 805, Business Combinations, the historical equity of AON LLC has been recasted in all periods up to the Closing Date, to reflect the number of shares of New AON’s Class A Common Stock and Class B Common Stock issued to Legacy AON Shareholders in connection with the Reverse Recapitalization. The Company recasted the units outstanding related to the historical AON LLC Class A, Class A-1, and Class B units prior to the Reverse Recapitalization (“Historical AON LLC Equity”) as common equity of New AON, equal to the Per Company Class Unit Exchange Ratio, pursuant to the Business Combination Agreement.

The Per Company Unit Exchange Ratio at which AON LLC Class A units and Class A-1 units were reclassified is equal to 2,524 AON Common Units. The Per Company Unit Exchange Ratio at which AON LLC Class B units were reclassified varied depending on participation threshold, and is equal to 2,524, 2,453, or 1,976, AON Common Units. The Per Company Unit Exchange Ratio at which Class C units were reclassified is equal to 2,705 AON LLC Series A Preferred Units.

The condensed consolidated financial statements and related notes thereto give effect to the conversion for all periods presented, without any change to par value or per unit amounts. The condensed consolidated financial statements do not necessarily represent the capital structure of New AON had the Reverse Recapitalization occurred in prior periods. The Company has not made retroactive adjustments related to the historical book values of Historical AON LLC Equity as the adjustments were considered immaterial.

For both the three and nine months ended September 30, 2023, $1.7 million of the consolidated net loss of AON LLC were attributable to the Class A Common Stockholders, and reflects the Class A Common Stockholders’ absorption of 19.0% of the consolidated net loss of AON LLC for the period of September 21, 2023 through September 30, 2023. For both the three and nine months ended September 30, 2023, $11.9 million of the consolidated net losses of AON LLC were attributable to the noncontrolling interest, and reflects the Legacy AON Shareholders’ absorption of 81.0% of the consolidated net losses of AON LLC for the period of September 21, 2023 through September 30, 2023. For the three and nine months ended September 30, 2023, $15.5 million and $27.0 million of the consolidated net losses of AON LLC were attributable to the Legacy AON Shareholders, respectively, to reflect their absorption of 100% of the consolidated net losses of AON LLC pertaining to the days prior to the Reverse Recapitalization. For the three and nine months ended September 30, 2022, net income of $5.6 million and $1.2 million were attributable to the Legacy AON Shareholders, respectively, to reflect their absorption of 100% of AON LLC’s net income pertaining to the periods prior to the Reverse Recapitalization.

Principles of Consolidation

For the period of September 21, 2023 through September 30, 2023, the condensed consolidated financial statements include the accounts of the Company, AON, Inc., American Oncology Network, LLC (“AON LLC”) and its wholly owned subsidiary American Oncology Management Company, LLC (“AOMC”), and its consolidated variable interest entities (“VIEs”) American Oncology Partners, P.A. (“AON Partners”), American Oncology Partners of Maryland, P.A. (“Partners of Maryland”), AON Central Services, LLC (“AON Central Services”), and Meaningful Insights Biotech Analytics, LLC (“MIBA”). All intercompany accounts and transactions between the entities have been eliminated in consolidation.

Refer to Note 1 for the accounting treatment of the Business Combination.

For the periods prior to the Reverse Recapitalization, the consolidated financial statements of the Company comprise the accounts of AON LLC and its wholly-owned subsidiaries. All intercompany accounts and transactions among AON LLC and its consolidated subsidiaries were eliminated.

The Company accounts for American Oncology Network, LLC, AON Partners, Partners of Maryland, AON Central Services, and MIBA in accordance with Financial Accounting Standards Board (“FASB”) Accounting

Standards Codification (“ASC”) 810, Consolidations. The Company determines whether it has a controlling financial interest in an entity by first evaluating whether the entity is a VIE. A VIE is broadly defined as an entity that has any of the following three characteristics: (i) the equity investment at risk is insufficient to finance the entity’s activities without additional subordinated financial support; (ii) substantially all of the entity’s activities either involve or are conducted on behalf of an investor that has disproportionately few voting rights; or (iii) the equity investors as a group lack any of the following, the power through voting or similar rights to direct the activities of the entity that most significantly impact the entity’s economic performance, the obligation to absorb the expected losses of the entity, or the right to receive the expected residual returns of the entity. The Company consolidates a VIE if it has both the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and an obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. Management performs ongoing reassessments of whether changes in the facts and circumstances regarding the Company’s involvement with a VIE will cause the consolidation conclusion to change. Changes in consolidation status are applied prospectively, if any.

AON LLC has contractual relationships with AON Partners, Partners of Maryland and AON Central Services and the physician owners through management service agreements (“MSAs”) and other contractual agreements to provide all practice management services outside of medical services provided by the physicians. In addition, despite not being required by the contractual relationships, AON LLC regularly provides funding to support AON Partners and Partners of Maryland’s operations and acquisitions of physician practices. AON Central Services was formed July 15, 2022 and, effective January 1, 2023, entered into an agreement with AOMC to provide qualified non-clinical and non-medical employees to AOMC to support the operation of the physician practices. MIBA was established during the first quarter of 2023 for the purpose of developing intellectual property to synergize the collection, de-identification, and dissemination of the Company’s patient data for sale to external parties for research, development, and clinical decisions. In May 2023, the Company contributed $0.2 million for a 56% interest in the equity of MIBA. As of September 30, 2023, MIBA had no significant operating activity. The Company concluded that AON LLC had a controlling financial interest in MIBA and has consolidated the entity at September 30, 2023 and recorded the noncontrolling interest in equity.

The Company has concluded that AON Partners, Partners of Maryland, AON Central Services, and MIBA are all VIEs in which AON LLC has the characteristics of a controlling financial interest and is deemed to be the primary beneficiary. The variable interest subjects AON LLC to all potential losses in the entities and, therefore, requires AON LLC, and in turn AON Inc., to consolidate the results of AON Partners, Partners of Maryland, AON Central Services, and MIBA in its condensed consolidated financial statements.

Refer to Note 4 for further information on the VIEs. Refer to Note 1 for the accounting treatment of the Reverse Recapitalization.

Significant Accounting Policies

The accounting policies included below should be read in conjunction with the annual consolidated financial statements.

Accounting Estimates and Assumptions

Segments

Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker (the “CODM”). The Company’s CODM is its chief executive officer who reviews financial information together with certain operating metrics principally to make decisions about how to allocate resources and to measure the Company’s performance. The Company has one operating segment and one reportable segment that are structured around the organizational management of oncology practice operations. All revenue and assets are in the United States.

Revenue Recognition

Revenue is recognized under Accounting Standards Update (“ASU”) 2014-09 Revenue from Contracts with Customers (“Topic 606”). The Company determines the transaction price based upon standard charges for goods and services with anticipated consideration due from patients, third-party payors (including health insurers and government agencies) and others. The Company’s revenue is primarily derived from patient service revenues, which encompass oncology services provided during patient visits and shipments of pharmacy prescriptions. Performance obligations for the Company’s services provided to patients and most procedures, are satisfied over the time of visit which is the same day services are performed. Performance obligations relating to pharmacy revenue are considered fully satisfied at a point in time upon the customer receiving delivery of the prescription. Accordingly, the Company does not anticipate a significant amount of revenue from performance obligations satisfied (or partially satisfied) in previous periods, and any such revenue recognized during the three and nine month periods ended September 30, 2023 and 2022 was immaterial. Additionally, the Company does not expect to recognize material revenue in the future related to performance obligations that are unsatisfied (or partially satisfied) as of September 30, 2023 and December 31, 2022. Approximately $238.9 million and $213.8 million and $678.1 million and $606.0 million of the Company’s revenues are generated from services performed during patient visits with the remainder primarily generated from shipments of pharmacy prescriptions for the three and nine month periods ended September 30, 2023 and 2022, respectively.

As services are performed and prescriptions are shipped, timely billing occurs for services rendered and prescriptions shipped less discounts provided to uninsured patients and contractual adjustments to third-party payors based upon prospectively determined rates and discounted charges. Payment is requested at the time of service for self-paying patients and for patients covered by third-party payors that are responsible for paying deductibles and coinsurance.

The Company monitors revenue and receivables to prepare estimated contractual allowances for the anticipated differences between billed and reimbursed amounts. Payments from third-party payors and Government programs including Medicare and Medicaid may be subject to audit and other retrospective adjustments. Such amounts are considered on an estimated basis when net patient revenue is recorded and are adjusted as final adjustments are determined. For the three and nine month periods ended September 30, 2023 and 2022, such resulting historic adjustments have been immaterial to the condensed consolidated financial statements.

In assessing who is the principal in providing patient services and pharmacy prescriptions, the Company considered who controls the provision of services and prescriptions. The Company has determined they are acting as a principal in these relationships.

In April 2022, the Company entered into a long-term arrangement to sponsor and manage a clinical trial. The Company subsequently contracted with a third-party to provide the clinical research services and is the principal in this arrangement. The performance of clinical research services are considered a single performance obligation because the Company provides a highly-integrated service. Revenue is recognized for the single performance obligation over time due to the Company’s right to payment for work performed to date. The contract provides for invoices based on predetermined milestones.

The Company uses the cost-to-cost measure of progress for the Company’s contract because it best depicts the transfer of control to the customer as the performance obligation is fulfilled. For this method, the Company compares the contract costs incurred to date to the estimated total contract costs through completion. As part of the client proposal and contract negotiation process, the Company develops a detailed project budget for the direct costs and reimbursable costs based on the scope of the work, the complexity of the study, the geographical location involved and the Company’s historical experience. The estimated total contract costs at the project level are reviewed and revised periodically throughout the life of the contract, with adjustments to revenue resulting from such revisions being recorded on a cumulative basis in the period in which the revisions are identified. Contract costs consist primarily of direct labor and other reimbursable project-related costs such as travel, third-party vendor costs and investigator fees. The Company establishes pricing based on the Company’s internal pricing guidelines, discount agreements, if any, and negotiations with the client. The transaction price is the contractually defined amount. Revenue related to the clinical trial, which is included within other revenue, was $2.2 million and $1.0 million and $3.7 million and $3.1 million for the three and nine months ended September 30, 2023 and 2022, respectively.

condensed consolidated statements of operations and comprehensive loss. The Company’s VBC revenue is primarily generated through its participation in the CMS Oncology Care Model (“OCM”) which is an episode-based payment model to promote high-quality cancer care. Participants enter six-month episode periods, and the Company bills a monthly fee during the six-month period based on a fixed rate per participant per month and the total number of participants. Certain quality and compliance metrics are tracked as part of the program and submitted to CMS at the end of the episode period which may result in recoupment of funds. The Company estimates the recoupment amount by developing a recoupment percentage for each period based on historical known recoupment from CMS and applies the recoupment percentage against total fees for the period. Based on the estimate, the Company accrues a liability representing the expected final recoupments based on historical settlement trends.

Short-term Marketable Securities

Investments in marketable securities consist of corporate bonds and U.S. Treasury securities.

Management determines the appropriate classification of investments at the time of purchase and reevaluates such determination at each balance sheet date. Marketable securities are classified as available-for-sale and are carried at fair value in the consolidated balance sheets. The marketable securities are classified as short-term based on management’s intent to convert such securities within one year and the ability to convert them within two to three days.

Certain of our available-for-sale securities are debt securities. For an available-for-sale debt security with an amortized cost that exceeds its fair value, the Company first determines if it intends to sell or will more-likely-than-not be required to sell the security before the expected recovery of its amortized cost. If it intends to sell or will more-likely-than-not be required to sell the security, then the Company recognizes the impairment as a credit loss in the condensed consolidated statements of operations and comprehensive loss by writing down the security’s amortized cost to its fair value. If it does not intend to sell or it is not more-likely-than-not that it will be required to sell the security before the expected recovery of its amortized cost, the Company recognizes the portion of the impairment that is due to a credit loss, if any, in the condensed consolidated statements of operations and comprehensive loss through an allowance. The portion of the impairment that is due to factors other than a credit loss is recognized in other comprehensive income (loss) in the condensed consolidated statements of operations and comprehensive loss as an unrealized loss.

Equity Investment in Affiliate

In January 2023, the Company contributed noncash consideration, with a fair value of approximately $2.3 million, in return for a 49% equity interest in OCP Management Arizona, LLP. Investments in entities over which the Company has the ability to exercise significant influence but does not control the entity are accounted for using the equity method. Equity method investments are included with other assets in the condensed consolidated balance sheets. The carrying amount of the investment is adjusted to reflect the Company’s proportionate share of the net earnings or losses and reduced by any dividends received. The Company’s share of income or loss related to this investment is reported as an equity in loss of affiliate in the condensed consolidated statements of operations and comprehensive loss.

Noncontrolling Interests

The Company consolidates the results of entities in which it has a controlling financial interest. Refer to Note 14 for additional considerations and presentation for noncontrolling interest.

Mezzanine Equity

New AON Series A Preferred Stock is redeemable for cash or the value of the property, rights or securities to be paid or distributed in the event of a Deemed Liquidation Event (which is outside of the Company’s control). As a result, Management has determined that the New AON Series A Preferred Stock should be classified as mezzanine equity. As of September 30, 2023, the Preferred Stock are recorded at their initial carrying value, net of offering costs of $0.8 million. The Series A Preferred Stock are not being accreted to redemption value, as the redemption is not probable. The Series A Preferred Stock are classified outside of members’ equity on the consolidated balance sheets. Refer to Note 14 for mezzanine equity presentation considerations for redeemable noncontrolling interest.

Business Combinations

The Company evaluates acquired practices in accordance with ASU 2017-01, Business Combinations (Topic 805)-Clarifying the Definition of a Business. This standard clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as

acquisitions or disposals of assets or businesses. Because substantially all of the value of each acquired practice did not relate to a similar group of assets and as each acquired practice contained both inputs and processes necessary to provide economic benefits to the Company, it was determined that each acquisition represents a business combination. Therefore, the transactions have been accounted for using the acquisition method of accounting, which requires, with limited exceptions, that assets acquired, and liabilities assumed be recognized at their estimated fair values as of the acquisition date. Any excess of the consideration transferred over the estimated fair values of the net assets acquired is recorded as goodwill. Transaction costs related to business combinations are expensed in the period in which they are incurred.

Offering Costs

The Company defers specific incremental costs directly attributable to proposed offerings of securities. These costs consist of legal, accounting, and other similar expenses incurred through the balance sheet date that are directly related to a potential offering. If the offering is completed, these costs will be charged against the gross proceeds of the offering. These offering costs will be allocated to the separable financial instruments issued in the transaction on a relative fair value basis of the securities issued, compared to total proceeds received. Offering costs associated with any instruments classified as liabilities will be expensed as incurred, presented as non-operating expenses in the condensed consolidated statement of operations and comprehensive loss.

During the nine months ended September 30, 2023, the Company incurred additional deferred offering costs of approximately $0.8 million which were recorded as an offset to the net proceeds of the AON LLC Class C Units (discussed below) in mezzanine equity on the condensed consolidated balance sheet at September 30, 2023. At December 31, 2022, the Company had incurred approximately $0.3 million of offering costs, which are included in other assets in the accompanying condensed consolidated balance sheets.

As discussed in Note 1, on June 7, 2023, AON LLC issued Redeemable Convertible Preferred Class C Units (“Class C Units” or “AON LLC Class C Units”) for net proceeds of approximately $64.5 million ($65.0 million in gross proceeds, net of $0.5 million in offering costs). The Company determined that an additional $0.3 million of costs incurred through June 7, 2023 related to the process of raising the proceeds generated by the issuance of the Class C Units. Accordingly, these deferred offering costs have been reclassified from other assets to mezzanine equity, for a total of $0.8 million in Class C Unit offering costs. The Class C Units were subsequently converted to AON LLC Series A Preferred Units upon the Closing of the Business Combination, which were subsequently exchanged for Series A Preferred Stock.

Professional Liability

The Company maintains insurance policies for exposure to professional malpractice insurance risk. The limits of malpractice insurance provide each physician/advanced practice provider with a dedicated $1.0 million limit per claim and a $3.0 million limit in the aggregate per policy period – on a first dollar basis, as no deductible applies. The policy further then extends coverage to the Company, by providing a $2.0 million limit per claim and a $4.0 million limit in the aggregate per policy period - on a first dollar basis, additionally, as no deductible applies. Reserves are established for estimates of the loss that will ultimately be incurred on claims that have been reported but not paid and claims that have been incurred but not reported. These reserves are established based on consultation with a third-party actuary. The actuarial valuations consider a number of factors, including historical claims payment patterns, changes in case reserves and the assumed rate of increase in healthcare costs. Management believes the use of actuarial methods to account for these reserves provides a consistent and effective way to measure these subjective accruals. However, due to the sensitive nature of this estimation technique, recorded reserves could differ from ultimate costs related to these claims due to changes in claims reporting, claims payment and settlement practices and differences in assumed future cost increases. Accrued unpaid claims and expenses that are expected to be paid within the next twelve months are classified as current liabilities and included in accrued other. All other accrued unpaid claims and expenses are classified as long-term liabilities and included in other long-term liabilities. Insurance recoveries associated with the unpaid claims are classified as long-term assets included in other assets.

Fair Value of Financial Instruments

Accounting guidance establishes a three-level hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability on the measurement date. The three levels are defined as follows:

Level 1

Inputs to the valuation methodology are quoted prices (unadjusted) for an identical asset or liability in an active market.

Level 2

Inputs to the valuation methodology include quoted prices for a similar asset or liability in an active market or model-derived valuations in which all significant inputs are observable for substantially the full term of the asset or liability.

Level 3

Inputs to the valuation methodology are unobservable and significant to the fair value measurement of the asset or liability. This includes certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs.

Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the placement of assets and liabilities being measured within the fair value hierarchy.

Our financial instruments include cash, short-term marketable securities, accounts receivable, notes receivable, accounts payable, accrued expenses, long-term debt and contractual agreements that resulted in derivative liabilities. Our nonfinancial assets such as property and equipment are not measured at fair value on a recurring basis; however, they are subject to fair value adjustments in certain circumstances, such as when there is evidence that impairment may exist.

The carrying amounts of cash, accounts receivable, accounts payable, notes receivable, and accrued expenses approximate their fair value because of the short-term maturity and highly liquid nature of these instruments. We determine the fair value of long-term debt and marketable securities based on various factors including maturity schedules and current market rates.

See Note 6 for a discussion of the Company’s Level 1 and Level 2 Marketable Securities as of September 30, 2023. See below for a discussion of the Company’s Level 1 and Level 3 warrant liabilities as of September 30, 2023. As of December 31, 2022, there were no Level 3 financial instruments. There were no transfers between any levels of the hierarchy during any periods presented.

Warrant Liabilities

The Company evaluated the Public Warrants and Private Placement Warrants and the Class B Prefunded Warrants, collectively referred to herein as “Warrants”, in accordance with ASC 815-40, “Derivatives and Hedging —- Contracts in Entity’s Own Equity”, and concluded that a provision in the warrant agreements related to potential net cash settlement of the warrants upon an exchange or tender offer that may not result in a change in control of the entity precludes the warrants from being accounted for as components of equity. As the Warrants meet the definition of a derivative as contemplated in ASC 815, the Warrants are recorded as long term liabilities on the condensed consolidated balance sheets and measured at fair value at inception and at each reporting date in accordance with ASC 820, “Fair Value Measurement”, with changes in fair value recognized in other income (expense), net on the condensed consolidated statements of operations and comprehensive loss in the period of change.

As of September 30, 2023, the Public Warrants were trading separately from the Class A Common Stock and the quoted market price was used to establish fair value. As such, the Public Warrants fair value was determined using a Level 1 input. The fair value of the Public Warrants is $1.4 million and recorded in other long-term liabilities on the condensed consolidated balance sheets.

Management has utilized the public warrant price to value the private warrants and believes the public and private warrants have materially consistent fair values given the existence of the make-whole redemption feature. As of September 30, 2023, a valuation of the private warrants was performed which confirmed the private warrant value was materially consistent with the public warrants. The details of this valuation are included in the paragraph below.

The fair value of the Private Placement warrants was determined using Level 3 inputs. As of September 30, 2023, the fair value of the Private Placement Warrants was estimated to be $1.0 million and recorded in other

long-term liabilities on the condensed consolidated balance sheets. The fair value was estimated at September 30, 2023, using the Black-Scholes Option Pricing model using the following assumptions:

Expected annual dividend yield			0.0%
Expected volatility			0.75%
Risk-free rate of return			4.60%
Expected Option Term			5.0

The AON Class B Prefunded Warrants are exercisable into one share of New AON Class B Common Stock. A share of New AON Class B Common Stock, together with an AON LLC Common Unit, may be exchanged for one share of New AON Class A Common Stock. Considering New AON Class B Common Stock has no economic rights and limited liquidity or value if the holder does not also possess an AON LLC Common Unit, and because the AON Class B Prefunded Warrants are exercisable into New AON Class B Common Stock, the Company has estimated fair value of the Class B Prefunded Warrants to be immaterial.

Earnings Per Share

The Company recast Historical AON LLC Equity as AON Inc. common equity for all periods prior to the Reverse Recapitalization, refer to Note 2. However, as 100% of the net losses of AON LLC prior to the Reverse Recapitalization were absorbed by the Legacy AON Shareholders, basic and diluted earnings (loss) per share is zero for the three and nine months ended September 30, 2022 and basic and diluted earnings (loss) per share for the three and nine months ended September 30, 2023 represents only the period from September 21, 2023 to September 30, 2023, the period where the Company had earnings (loss) attributable to Class A Common Stockholders. Class B Common Stock does not have economic rights in AON Inc., including rights to dividends or distributions upon liquidation, and as a result, is not considered a participating security for basic and diluted earnings (loss) per share. As such, basic and diluted earnings (loss) per share of Class B Common Stock has not been presented.

As discussed in Note 1, the Company has issued and outstanding Sponsor Earnouts, which are subject to forfeiture if the achievement of certain stock price thresholds are not met. In accordance with ASC Topic 260, “Earnings Per Share,” the Sponsor Earnouts are excluded from weighted-average shares outstanding to calculate basic earnings (loss) per share as they are considered contingently issuable shares due to their potential forfeiture. Sponsor Earnouts will be included in weighted-average shares outstanding to calculate basic earnings (loss) per share as of the date of their stock price thresholds are met and they are no longer subject to forfeiture.

Basic and diluted earnings (loss) per share is computed by use of the two-class method as a result of outstanding Series A Preferred Stock, which accrue dividends at the annual rate of 8% of the original price per share, participate with common stock on all other dividends, and accordingly have participation rights in undistributed earnings as if all such earnings had been distributed during the period (see Note 12). Under such method income available to common shareholders is computed by deducting both dividends declared or, if not declared, accumulated on Series A Preferred Stock from net income. Loss attributable to common shareholders is computed by increasing net loss by such dividends. Since the participating Series A Preferred Stock has no contractual obligation to share in the losses of the Company, there is no loss allocation between Class A Common Stock and Series A Preferred Stock.

Basic earnings (loss) per share is based on the weighted-average number of shares of Class A Common Stock outstanding during the period. Diluted earnings (loss) per share is based on the weighted-average number of shares of Class A Common Stock used for the basic earnings (loss) per share calculation, adjusted for the dilutive effect of the Public and Private Warrants and Sponsor Earnout, if any, using the “treasury stock” method and the convertible Series A Preferred Stock and, exchangeable Class B Common Stock and Class B Prefunded Warrants, if any, using the “if-converted” method. Net earnings (loss) for diluted loss per share is adjusted for the Company’s share of AON LLC’s consolidated net earnings (loss), net of AON Inc. taxes, after giving effect to the Class B Common Stock and Class B Prefunded Warrants that are exchanged into potential shares of Class A Common Stock, Public and Private Warrants that are liability classified, and Series A Preferred Stock, to the extent it is dilutive.

Recently Adopted Accounting Pronouncements

In June 2016, the FASB issued ASU 2016-13, “Financial instruments-Credit Losses” (“ASU 2016- 13”). ASU 2016-13 requires entities to report “expected” credit losses on financial instruments and other commitments to extend credit rather than the current “incurred loss” model. These expected credit losses for financial assets held at

the reporting date are to be based on historical experience, current conditions, and reasonable and supportable forecasts. This ASU will also require enhanced disclosures relating to significant estimates and judgments used in estimating credit losses, as well as the credit quality. ASU 2016-13 is effective for the Company for annual reporting periods beginning after December 15, 2022. ASU 2016-13 was adopted by the Company effective January 1, 2023 with no material impact on the Company’s consolidated financial statements and related disclosures.

Recently Issued Accounting Pronouncements

In October 2021, the FASB issued ASU 2021-08, “Business Combinations: Accounting for Contract Assets and Contract Liabilities from Contracts with Customers”, which provides that an acquirer must recognize, and measure contract assets and contract liabilities acquired in a business combination in accordance with ASC 606. The guidance is effective for the Company for annual reporting periods beginning after December 15, 2023, with early adoption permitted. The Company does not expect the adoption of this standard to have a material impact on the Company’s consolidated financial statements and related disclosures.

Related Parties, Inventory Purchases/Concentration Risk (FY) (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2022

Dec. 31, 2021

Dec. 31, 2020

Sep. 30, 2023

Inventory Purchases/Concentration Risk [Abstract]

Purchase of inventories

$ 924,000

$ 731,000

$ 574,000

106,495

^[1],[2]

92,908

^[2]

$ 120,383

^[1]

Inventory Purchases/Concentration Risk [Abstract]

Inventory Purchases/Concentration Risk [Abstract]

$ 102,113

$ 88,799

$ 112,740

Concentration risk percentage

88.00%

83.00%

88.00%

Inventory Purchases/Concentration Risk [Abstract]

Concentration risk percentage

96.00%

[1]	Includes amounts due to related party of $112,740 and $102,113 at September 30, 2023 and December 31, 2022, respectively
[2]	Includes amounts due to related party of $102,113 and $88,799 at December 31, 2022 and 2021, respectively

Marketable Securities (Q3)

9 Months Ended

Sep. 30, 2023

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

6. Marketable Securities

The following table summarizes the Company’s marketable securities financial assets that are measured at fair value on a recurring basis:

	As of September 30, 2023
	Amortized Cost	Gross Unrealized Gains	Gross Unrealized Losses	Estimated Fair Value
Cash equivalents⁽¹⁾
Level 1:
Overnight repurchase agreements⁽²⁾	$28,272	$—	$—	$28,272
Money market funds	773	—	—	773
U.S. Treasury Bills	18,606	—	—	18,606
Level 1 total	$47,651	$—	$—	$47,651
Marketable securities
Level 2:
Corporate bonds	13,980	62	(38)	14,004
U.S. Treasury securities	11,981	52	(4)	12,029
Level 2 total	25,961	114	(42)	26,033
Total	$73,612	$114	$(42)	$73,684

	As of December 31, 2022
	Amortized Cost	Gross Unrealized Gains	Gross Unrealized Losses	Estimated Fair Value
Cash equivalents⁽¹⁾
Level 1:
Money market funds	$109	$—	$—	$109
Marketable securities
Level 2:
Corporate bonds	7,742	6	(125)	7,623
U.S. Treasury securities	2,226	6	(4)	2,228
Level 2 total	9,968	12	(129)	9,851
Total	$10,077	$12	$(129)	$9,960

(1)	Included in cash and cash equivalents in the Consolidated Balance Sheets at September 30, 2023 and December 31, 2022.

(2)

Cash equivalents as of September 30, 2023 included U.S. Treasury Bills with an initial maturity of 3 months or less and overnight repurchase agreements in which cash from the Company's main operating checking account is invested overnight in highly liquid, short-term investments sponsored by a large financial institution. The company had no such investments as of December 31, 2022.

The Company uses quoted prices in active markets for identical assets to determine the fair value of its Level 1 investments. The fair value of the Company’s Level 2 investments is determined using pricing based on quoted market prices or alternative market observable inputs.

The fair value of the Company’s marketable securities as of September 30, 2023, by remaining contractual maturities, were as follows:

	Corporate Bonds	U.S. Treasuries	Total
Due in one year or less	$4,805	$8,385	$13,190
Due in one to five years	9,199	3,644	12,843
Total	$14,004	$12,029	$26,033

Business (FY)

12 Months Ended

Dec. 31, 2022

Schedule of Reverse Recapitalization, Changes in Units

Business

1. Business

American Oncology Network, Inc. (“AON”, “New AON”, “AON Inc.”, or the “Company”), through its subsidiary company and variable interest entities (together, “its subsidiaries”), is an alliance of physicians and seasoned healthcare leaders who provide comprehensive oncology services through 24 oncology practices located in Arkansas, Louisiana, Indiana, Virginia, Ohio, Nevada, Iowa, Missouri, Washington, North Carolina, Michigan, Maryland, South Carolina, Arizona, and Georgia. The Company also provides expertise in drug procurement and payor contracting, along with practice diversification through centralized laboratory and pathology services, as well as specialty pharmacy services. During the years ended December 31, 2022, 2021, and 2020, respectively, the Company entered into affiliation agreements with or acquired the following oncology practices. The operations of the practices that were acquired have been included in the Company’s consolidated financial statements since the date of acquisition. The Company intends to continue to pursue additional purchases of physician practices in addition to seeking out new affiliation relationships.

State

Effective

Date

State

Effective

Date

State

Effective

Date

Location 12

North

Carolina

4/1/2020

Location 18

Maryland

3/1/2021

Location 23

Arizona

1/1/2022

Location 13

Maryland

5/1/2020

Location 19

Arizona

4/1/2021

Location 24

Georgia^(a)

1/1/2022

Location 14

Virginia

5/1/2020

Location 20

Washington

5/1/2021

Location 25

Louisiana^(a)

1/17/2022

Location 15

Michigan

7/1/2020

Location 21

Georgia^(a)

8/1/2021

Location 26

Georgia^(a)

4/5/2022

Location 16

Washington

8/1/2020

Location 22

Arizona

11/1/2021

Location 27

Georgia^(a)

5/1/2022

Location 17

Georgia and

South

Carolina

9/1/2020

Location 28

Georgia^(a)

9/20/2022

(a)	The Company entered into affiliation agreements with the physicians for these respective practices. The Company evaluated each of the affiliation agreements and determined that the transactions did not represent a business combination.

Equity (Q3) (Tables)

9 Months Ended

Sep. 30, 2023

Stockholders' Equity [Abstract]

The following table summarizes the changes to AON LLC’s Class A, Class A-1, and Class B Units for the three and nine months ended September 30, 2023, and 2022.

in thousands, except for share and per share amounts	Three Months Ended September 30,		Nine Months Ended September 30,
	2023	2022	2023	2022
Class A Units, value
Beginning of Period	$7,725	$7,725	$7,725	$7,725
Issuance of Units	—	—	—	—
Impact of the Reverse Recapitalization	(7,725)	—	(7,725)	—
End of Period	$—	$7,725	$—	$7,725
Class A Units, units
Beginning of Period	19,495,376	19,495,376	19,495,376	19,495,376
Issuance of Units	—	—	—	—
Impact of the Reverse Recapitalization	(19,495,376)	—	(19,495,376)	—
End of Period	—	19,495,376	—	19,495,376

in thousands, except for share and per share amounts	Three Months Ended September 30,		Nine Months Ended September 30,
	2023	2022	2023	2022
Class A-1 Units, value
Beginning of Period	$31,040	$28,500	$28,500	$28,500
Issuance of Units	7,185	—	9,725	—
Impact of the Reverse Recapitalization	(38,225)	—	(38,225)	—
End of Period	$—	$28,500	$—	$28,500
Class A-1 Units, units
Beginning of Period	2,281,696	1,842,520	1,842,520	1,842,520
Issuance of Units	718,549		1,157,725
Impact of the Reverse Recapitalization	(3,000,245)		(3,000,245)
End of Period	—	1,842,520	—	1,842,520

in thousands, except for share and per share amounts	Three Months Ended September 30,		Nine Months Ended September 30,
	2023	2022	2023	2022
Class B Units, value
Beginning of Period	$80	$90	$80	$80
Equity based compensation	10	5	10	15
Impact of the Reverse Recapitalization	(90)	—	(90)
End of Period	$—	$95	$—	$95
Class B Units, units
Beginning of Period	4,703,628	4,703,628	4,703,628	4,703,628
Units Vested	910,548	—	910,548	—
Impact of the Reverse Recapitalization	(5,614,176)	—	(5,614,176)	—
End of Period	—	4,703,628	—	4,703,628

Business Combinations (Q3) (Details) - Northern Arizona Hematology and Oncology - USD ($)	Jan. 01, 2022	Sep. 30, 2023	Dec. 31, 2022
Business Acquisition [Line Items]
Purchase price (less than)	$ 100,000
Unwind agreement, liability		$ 0	$ 0

Other Receivables (FY) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Other Receivables [Abstract]
Rebates receivable		$ 27,955	$ 24,950
Other		246	128
Total other receivables	$ 36,747	$ 28,201	$ 25,078

Summary of Significant Accounting Policies and Basis of Presentation (FY) (Tables)

12 Months Ended

Dec. 31, 2022

Summary of Significant Accounting Policies and Basis of Presentation [Abstract]

Cash, Cash Equivalents and Restricted Cash

The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the Consolidated Balance Sheets that sum to the total of the same cash amounts shown in the Consolidated Statements of Cash Flows.

	As of December 31,
	2022	2021
Cash and cash equivalents	$26,926	$27,354
Restricted cash	—	5,000
Total cash, cash equivalents and restricted cash shown in the statements of cash flow	$26,926	$32,354

Concentrations of Accounts Receivable, Net of Allowances

Concentrations of accounts receivable, net of allowances for contractual discounts and doubtful accounts, as of December 31, 2022 and 2021, are as follows:

	As of December 31,
	2022	2021
Medicare	25%	27%
Managed Medicare	25%	21%
Other Commercial	17%	17%
BCBS	17%	16%
Managed Medicaid	8%	12%
Other	8%	7%
	100%	100%

Estimated Useful Lives

Property and equipment are recorded at cost and depreciated using the straight-line method over the estimated useful lives of the assets. A summary of the lives used for computing depreciation is as follows:

Leasehold improvements			1 – 15 years
Furniture, fixtures and equipment			7 years
Medical equipment			5 – 10 years
Computer equipment			5 years
Signs			7 years
Automobiles			5 years
Software			7 years

Summary of Significant Accounting Policies and Basis of Presentation, Debt Issuance Costs (FY) (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Debt Issuance Costs [Abstract]
Debt issuance costs	$ 570	$ 458	$ 627	$ 363	$ 19

Related Parties (Q3)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Related Parties

11. Related Parties

Transactions Notes Receivable

The Company enters into promissory notes with physicians of the Company. The notes receivable balances are satisfied through cash payments or settlements through the physicians’ compensation as part of their employee agreement. The notes receivable are amortized over a 60-month period as a reduction of compensation. The notes bear interest at the Company’s incremental borrowing rate (7.14% at September 30, 2023 and 1.57% at December 31, 2022, respectively).

	As of September 30, 2023	As of December 31, 2022	Original Principal	Issue Date	Maturity Date
Notes receivable
Note 2	$1,027	$1,057	$5,355	5/1/2019	4/30/2024
Note 3	42	119	491	6/1/2019	5/31/2024
Note 6	—	351	1,111	5/22/2020	5/22/2023
Note 8	2,065	2,221	2,816	5/1/2020	5/1/2025
Note 9	—	125	125	1/24/2022	6/30/2023
Total notes receivables	3,134	3,873
Less: Current portion of notes receivable	$(1,630)	(1,797)
Notes receivable, less current portion	$1,504	$2,076

Leases

The Company has operating leases for ten of the office facilities owned by employees of the Company. Total cash was approximately $0.6 million and $1.9 million paid for leases to related parties for the both the three and nine months ended September 30, 2023 and 2022, respectively.

Inventory Purchases/Concentration Risk

The Company purchases the majority of pharmaceuticals inventory from a subsidiary under common control of a Legacy AON Shareholder. During the three and nine months ended September 30, 2023 and 2022, the Company purchased from the related party approximately $268.0 million and $239.0 million and $774.0 million and $682.0 million, respectively. These purchases were approximately 86% and 89% and 88% and 86% as a percentage

of cost of revenue for the three and nine months ended September 30, 2023 and 2022, respectively. At September 30, 2023 and December 31, 2022, the Company had $113.0 million and $102.1 million, respectively, included in accounts payable for invoices from the related party, representing 94% of accounts payable at each period-end.

14. Related Parties

Transactions Notes Receivable

The Company entered into promissory notes with physicians of the Company. The notes receivable balances are satisfied through cash payments or settlements through the physicians’ compensation as part of their employee agreement. The notes receivable are amortized over a 60-month period as a reduction of compensation. The notes bear interest at the Company’s incremental borrowing rate (1.57% at December 31, 2022 and 1.55% at December 31, 2021).

	As of December 31,		Original Principal	Issue Date	Maturity Date
	2022	2021	Original Principal	Issue Date	Maturity Date
Notes receivable
Note 2	$1,057	$1,294	$5,355	5/1/2019	4/30/2024
Note 3	119	217	491	6/1/2019	5/31/2024
Note 4	—	259	917	8/1/2019	7/31/2024
Note 6	351	680	1,111	5/22/2020	5/22/2023
Note 8	2,221	2,513	2,816	5/1/2020	5/1/2025
Note 9	125	—	125	1/24/2022	6/30/2023
Total notes receivables	3,873	4,963
Less: Current portion of notes receivable	(1,797)	(1,812)
Notes receivable, less current portion	$2,076	$3,151

Leases

The Company has operating leases for office facilities owned by employees of the Company. Total cash paid for leases to related parties for the years ended December 31, 2022, 2021, and 2020 was approximately $2.5 million, $2.3 million and $6.8 million, respectively.

Inventory Purchases/Concentration Risk

The Company purchases the majority of its pharmaceuticals inventory from a subsidiary under common control of the Class A-1 Member, which made an equity investment in AON in 2020. During the years ended December 31, 2022, 2021 and 2020, the Company purchased approximately $924.0 million, $731.0 million, and $574.0 million, respectively, from the related party. These purchases were approximately 88%, 83% and 88% as a percentage of cost of revenue for the years ended December 31, 2022, 2021 and 2020, respectively. At December 31, 2022 and 2021, the Company had $102.1 million and $88.8 million, respectively, included in accounts payable for invoices from the related party, representing 96% of total accounts payable at each balance sheet date.

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-6

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(e))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//850/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-6

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

Recently Adopted/ Issued Accounting Pronouncements [Abstract]

Summary of Significant Accounting Policies and Basis of Presentation, Restricted Cash (FY) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Restricted Cash [Abstract]
Cash and cash equivalents	$ 51,653	$ 26,926		$ 27,354
Restricted cash		0		5,000
Total cash, cash equivalents and restricted cash shown in the statements of cash flow	$ 51,653	$ 26,926	$ 36,683	$ 32,354	$ 42,842	$ 4,013

Summary of Significant Accounting Policies and Basis of Presentation, Professional Liability (FY) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Professional Liability [Abstract]
Malpractice insurance, limit per claim	$ 1.0
Malpractice Insurance, Annual Coverage Limit First Dollar Basis	3.0
Malpractice insurance, extended coverage limit per claim	2.0
Malpractice insurance extended coverage limit in aggregate per policy period	$ 4.0

Summary of Significant Accounting Policies and Basis of Presentation, Recently Adopted/ Issued Accounting Pronouncements (FY) (Details) - USD ($)
$ in Thousands

Sep. 30, 2023

Dec. 31, 2022

Dec. 31, 2021

Operating ROU assets

$ 46,138

^[1]

$ 43,724

^[1],[2]

$ 0

^[2]

3,445

2,670

3,277

7,123

^[3]

9,177

^[3],[4]

^[4]

Finance lease, ROU assets

42,261

^[5]

37,224

^[5],[6]

^[6]

2,791

1,998

Finance lease, lease liabilities

2,756

2,044

Recently Adopted/ Issued Accounting Pronouncements [Abstract]

$ 10,333

5,749

$ 5,717

ASU 2016-02 [Member]

Operating ROU assets

44,400

(1,200)

8,000

Finance lease, ROU assets

38,000

2,500

Finance lease, lease liabilities

2,500

$ 2,800

[1]	Includes related party operating right-of-use assets, net of $11,476 and $13,077 at September 30, 2023 and December 31, 2022, respectively
[2]	Includes related party operating lease right-of-use assets, net of $13,077 at December 31, 2022
[3]	Includes related party current portion of operating lease liabilities of $1,912 and $1,836 at September 30, 2023 and December 31, 2022, respectively
[4]	Includes related party current portion of operating lease liabilities of $1,836 at December 31, 2022
[5]	Includes related party long-term operating lease liabilities of $9,994 and $11,631 at September 30, 2023 and December 31, 2022, respectively
[6]	Includes related party long-term operating lease liabilities of $11,631 at December 31, 2022

Leases (Q3) (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Lessee, Assets And Liabilities

Right-of-use assets and lease liabilities consist of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
Assets
Operating lease right-of-use assets, net	$46,138	$43,724
Finance lease right-of-use assets, net (included in property and equipment, net)	2,791	1,998
Total right-of-use assets	$48,929	$45,722
Liabilities
Current
Current portion of operating lease liabilities	$7,123	$9,177
Current portion of finance lease liabilities (included in accrued other)	630	425
Long-term	7,753	9,602
Long-term operating lease liabilities	42,261	37,224
Long-term finance lease liabilities (included in other long-term liabilities)	2,126	1,619
Total lease liabilities	$52,140	$48,445

Lease, Cost

	Three Months Ended September 30,		Nine Months Ended September 30,
	2023	2022	2023	2022
Operating lease costs	$2,820	$3,161	$8,361	$9,297
Finance lease costs
Amortization of finance lease right-of-use assets	122	185	354	413
Interest on finance lease liabilities (included in interest expense)	35	19	79	60
Variable lease costs	560	862	1,742	2,232
Total lease costs	$3,537	$4,227	$10,536	$12,002

The cash paid for amounts included in the measurement of lease liabilities for the nine months ended September 30, 2023 and 2022 is as follows:

	Nine Months Ended September 30,
	2023	2022
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$7,678	$9,788
Operating cash flows from finance leases	79	60
Financing cash flows from finance leases	387	321
ROU assets obtained in exchange for new operating lease liabilities	9,862	9,771
ROU assets obtained in exchange for new finance lease liabilities	1,103	—

The components of lease costs recognized in the Consolidated Statements of Operations and Comprehensive Income (Loss) consist of the following for the year ended December 31, 2022:

Operating lease costs			$12,465
Finance lease costs
Amortization of finance lease right-of-use assets			523
Interest on finance lease liabilities (included in interest expense)			79
Variable lease costs			2,737
Total lease costs			$15,804

Lessee, Operating Lease, Liability, to be Paid, Maturity

The following table reconciles the undiscounted cash flows expected to be paid in each of the next five years and thereafter recorded in the condensed consolidated balance sheets for operating and finance leases as of September 30, 2023:

	Operating Lease	Finance Leases
2023 (remainder of year after September 30, 2023)	$1,679	$188
2024	10,940	753
2025	9,830	731
2026	9,413	492
2027	8,194	428
Thereafter	24,154	528
Total lease payments	64,210	3,120
Less: amount representing interest	(14,826)	(364)
Present value of lease liabilities	49,384	2,756
Less: current portion of lease liabilities	(7,123)	(630)
Long-term lease liabilities, net of current portion	$42,261	$2,126

Finance Lease, Liability, to be Paid, Maturity

	Operating Lease	Finance Leases
2023 (remainder of year after September 30, 2023)	$1,679	$188
2024	10,940	753
2025	9,830	731
2026	9,413	492
2027	8,194	428
Thereafter	24,154	528
Total lease payments	64,210	3,120
Less: amount representing interest	(14,826)	(364)
Present value of lease liabilities	49,384	2,756
Less: current portion of lease liabilities	(7,123)	(630)
Long-term lease liabilities, net of current portion	$42,261	$2,126

Professional Liability Insurance (FY) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Malpractice Insurance [Abstract]
Maximum insurance coverage amount per incident		$ 2.0	$ 2.0
Annual agreegate amount of insurance coverage for each physician		4.0	4.0
Malpractice insurance recovery balance		2.2	1.0
Malpractice insurance reserve liability balance		3.7	2.2
Net tail liability		1.6	1.1
Physician [Member]
Malpractice Insurance [Abstract]
Maximum insurance coverage amount per incident	$ 1.0	1.0	1.0
Annual agreegate amount of insurance coverage for each physician	$ 3.0	$ 1.0	$ 1.0

Income Taxes (FY)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Income Taxes [Abstract]

Income Taxes

9. Income Taxes

The Company is a member of American Oncology Network, LLC, which is treated as a partnership for U.S. federal and certain state and local income taxes. As a partnership, American Oncology Network, LLC is not subject to U.S. federal and certain state and local income taxes. Any taxable income or loss generated by American Oncology Network, LLC is passed through to and included in the taxable income or loss of its members, including the Company, on a pro-rata basis.

The Company is subject to U.S. federal income taxes, in addition to state and local income taxes with respect to the allocable share of any taxable income of American Oncology Network, LLC. Additionally, other corporate entities within the Company's structure are subject to income taxes. These corporate entities continue to generate losses and continue to maintain a valuation allowance against their net deferred tax assets.

The Company’s effective income tax rate was (1.1)% and —% for the three months ended September 30, 2023 and 2022, respectively. The provision for income taxes was $315 and $0 for the three months ended September 30, 2023 and 2022, respectively.

The Company’s effective income tax rate was (0.8)% and —% for the nine months ended September 30, 2023 and 2022, respectively. The provision for income taxes was $315 and $0 for the nine ended September 30, 2023 and 2022, respectively.

The change to the income tax provision for the three and nine months ended September 30, 2023 compared to the income tax provision for the three and nine months ended September 30, 2022 was primarily a result of the transaction closing on September 20, 2023, resulting in a portion of the Company's consolidated pre-tax earnings, which were previously not subject to income taxes, flowing into a taxable corporation included in the Company's post transaction structure.

The effective income tax rate for the three and nine months ended September 30, 2023 and 2022 differed from the federal statutory rate primarily due to certain legal entities in the Company's structure being treated as partnerships for income tax purposes and, therefore, a significant portion of its income not being subject to income tax. Additionally, certain corporate entities within the Company's structure continue to maintain a full valuation allowance against their net deferred tax assets.

13. Income Taxes

The income tax expense (benefit) in 2022, 2021, and 2020 consisted of the following:

	Year Ended December 31,
	2022	2021	2020
Current
Federal	$—	$(306)	$152
State	—	(20)	123
	—	(326)	275
Deferred
Federal	—	433	(922)
State	—	353	(136)
	—	786	(1,058)
Total income tax expense (benefit)	$—	$460	$(783)

The differences between the federal tax rate and the Company’s effective tax rate for the years ended December 31, 2022, 2021, and 2020 are as follows:

	Year Ended December 31,
	2022	2021	2020
Federal statutory income tax rate	21.00%	21.00%	21.00%
State taxes, net of federal benefit	(11.94)	(97.95)	(0.80)
State rate change	(2.15)	(3.41)	0.07
Other	(3.71)	3.00	0.07
Nontaxable passthrough LLC income	(87.14)	(658.26)	(27.31)
Increase in valuation allowance	83.94	864.95	3.26
Effective tax rate	—%	129.33%	(3.71)%

Components of the net deferred tax assets and liabilities at December 31, 2022 and 2021 are as follows:

	As of December 31,
	2022	2021
Deferred tax assets
Net operating loss carryforwards	$6,589	$5,166
Accrued expenses	165	426
Deferred tax assets	6,754	5,592
Valuation allowance	(5,835)	(3,662)
Net deferred tax asset	919	1,930
Deferred tax liabilities
Prepaid expenses	—	64
Accounting method change	918	1,866
Fixed assets	1	—
Deferred tax liabilities	919	1,930
Net deferred tax asset	$—	$—

As of December 31, 2022, the Company had federal and state net operating loss (“NOL”) carryforwards of $25.4 million and $26.8 million, respectively. As of December 31, 2021, the Company had federal and state NOL carryforwards of $20.1 million and $20.5 million, respectively. The federal NOL carryforwards can be carried forward indefinitely and the state NOL carryforwards begin to expire in 2028.

During the years ended December 31, 2022 and 2021, the Company recorded an increase in the valuation allowance of $2.2 million and $3.0 million, respectively. The increase is primarily related to additional tax losses generated during the year.

As of December 31, 2022 and 2021, there are no liabilities related to uncertain tax positions. The Company recognizes interest and penalties related to unrecognized tax liabilities as a component of income tax expense, if any. The Company recognized no material interest and penalties during the years ended December 31, 2022, 2021, and 2020 and had no accrued interest or penalties as of December 31, 2022 and 2021.

The Company files income tax returns in the U.S. Federal jurisdiction and various state and local jurisdictions. The U.S. Federal and state and local tax returns are subject to examination for years 2019 and later. The Company does not currently have any open audits.

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482526/740-270-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

Redeemable Noncontrolling Interest

Business Combinations, 2021 Acquisitions (FY) (Details) - Asset Purchase Agreements with Four Oncology Practices [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) OncologyPractice
Asset Acquisitions [Abstract]
Number of oncology practices acquired \| OncologyPractice	4
Percentage of assets acquired	100.00%
Purchase Consideration [Abstract]
Cash transferred upon closing	$ 3,215
Assumed capital lease liabilities	1,097
Total consideration transferred	4,312
Net Assets Acquired [Abstract]
Inventories	2,211
Other assets	180
Property and equipment	1,371
Total net assets acquired	3,762
Amount assigned to goodwill	$ 550

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) (FY) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Costs and expenses
Rent expense	$ 12,465
Related Party [Member]
Costs and expenses
Inventory expense	922,148	$ 718,675	$ 567,782
Rent expense	$ 2,643	$ 2,319	$ 6,845

Redeemable Noncontrolling Interest (Q3)

9 Months Ended

Sep. 30, 2023

Noncontrolling Interest [Abstract]

14. Redeemable Noncontrolling Interest

Legacy AON Shareholders own 28,109,796 AON LLC Common Units, equal to a 67.9% of the economic interest in AON LLC. Legacy AON Shareholders also own 25,109,551 shares of Class B Common Stock and 3,000,245 Class B Prefunded Warrants, which, together with the AON LLC Common Units, may be redeemed at the option of the Legacy AON Shareholder on a one-for-one basis for shares of Class A Common Stock or the cash equivalent thereof (based on the market price of the shares of Class A Common Stock at the time of redemption) as determined by New AON. If New AON elects the redemption to be settled in cash, the cash used to settle the redemption must be funded through a private or public offering of Class A Common Stock no later than ten (10) business days after the redemption notice date. Upon the redemption of the AON LLC Common Units and Class B

Common Stock for shares of Class A Common Stock or the equivalent thereof, all redeemed shares of Class B Common Stock will be cancelled. The redemption value is determined based on a five-day volume weighted average price (“VWAP”) of the Class A common shares, subject to customary conversion rate adjustments for share splits, share dividends, and similar events affecting Class A Common Stock.

When applying SEC guidance concerning mezzanine classification, the Company understands that due to the NCI holders having control of the Board, if there is a sequence of remotely possible events that could trigger a redemption, this requires the instrument to be classified as temporary equity, without any regard to probability. Accordingly, though the redemption would require such a remotely possible sequence of events, and such remote sequence of events would also require, in management’s view, the Company to take extraordinary actions in order to allow such sequence of events to be remotely possible, the noncontrolling interest is currently classified as temporary equity. In the event that the Legacy AON Shareholders own less than 50% of the outstanding economic interest in AON LLC Common Units due to future redemptions, the noncontrolling interest will be presented as permanent equity.

The redeemable noncontrolling interest is recognized at the greater of (1) its initial fair value plus accumulated earnings/(losses) associated with the noncontrolling interest or (2) the redemption value as of the balance sheet date.

At September 30, 2023, the redeemable noncontrolling interest was recorded based on its redemption value of $369.3 million which exceeded its carrying value by $344.3 million. This measurement adjustment decreased additional paid in capital by $17.6 million and retained earnings (deficit) by $326.7 million.

The following table summarizes the economic ownership of AON LLC, for the period beginning September 20, 2023, the Closing Date of the Reverse Recapitalization, and ending September 30, 2023 (Refer to Note 1).

	Period beginning September 20, 2023 and ending September 30, 2023
		AON LLC Units
	AON Inc.	Legacy AON Shareholders	Total
Beginning of Period	—	—	—
Common Units Issued⁽¹⁾	6,614,229	28,109,796	34,724,025
Series A Preferred Units Issued	6,651,610	—	6,651,610
Total Units Issued	13,265,839	28,109,796	41,375,635
End of Period	13,265,839	28,109,796	41,375,635
Allocation of income to controlling and noncontrolling interests	32.1%	67.9%	100%
Allocation of losses to controlling and noncontrolling interests⁽²⁾	19.0%	81.0%	100%

(1)	The 6,614,229 of AON Inc. Common Units excludes 2,839,375 units, which is equivalent to the number of Sponsor Earnout Shares, that do not participate in profits and losses and are not included in the controlling interest percentage.

(2)

As discussed in Note 13, Series A Preferred Stock are considered participating securities for basic and diluted loss per share, but do not participate in losses. As a result, the consolidated net loss of AON LLC, during the period of September 21, 2023 through September 30, 2023, were allocated to the NCI to reflect the absorption of the Legacy AON Shareholders to a portion of the consolidated net loss of AON LLC. Net losses were not attributed to Series A Preferred Stock.

Leases - Supplemental Cash Flow Information (Q3) (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 7,678	$ 9,788	$ 12,590
Operating cash flows from finance leases	79	60	79
Financing cash flows from finance leases	387	321	426	$ 205	$ 0
ROU assets obtained in exchange for new lease liabilities
ROU assets obtained in exchange for new operating lease liabilities	9,862	9,771	$ 9,811
ROU assets obtained in exchange for new finance lease liabilities	$ 1,103	$ 0

CONSOLIDATED BALANCE SHEETS (FY) - USD ($)
$ in Thousands

Dec. 31, 2022

Dec. 31, 2021

Current assets

Short-term marketable securities

$ 26,926

$ 27,354

9,851

Restricted cash

5,000

136,098

111,226

36,476

34,529

Prepaids expenses and other current assets

28,201

25,078

2,670

3,277

Current portion of notes receivable - related parties

$ 1,797

$ 1,812

Financing Receivable, after Allowance for Credit Loss, Current, Related Party, Type [Extensible Enumeration]

Related Party [Member]

Total current assets

$ 242,019

$ 208,276

Operating right of use assets, net

31,980

32,648

^[2]

43,724

^[1]

Notes receivable - related parties

$ 2,076

$ 3,151

Financing Receivable, after Allowance for Credit Loss, Noncurrent, Related Party, Type [Extensible Enumeration]

Related Party [Member]

$ 5,199

$ 3,111

1,230

1,112

326,228

248,298

Current liabilities

^[4]

106,495

^[3]

92,908

7,466

8,901

17,800

13,792

Current portion operating lease liability

3,742

^[6]

9,177

^[5]

Total current liabilities

140,938

119,343

Commitments and contingencies (Note 16)

^[8]

37,224

^[7]

Long-term debt, net

80,301

63,694

5,749

5,717

264,212

188,754

Accumulated other comprehensive loss

(117)

Retained earnings

25,828

23,239

Total members' equity

62,016

59,544

Total liabilities and members' equity

326,228

248,298

Class A Units [Member]

Units outstanding

7,725

Class A-1 Units [Member]

Units outstanding

28,500

Class B Units [Member]

Variable Interest Entities [Abstract]

Units outstanding

$ 80

[1]	Includes related party operating right-of-use assets, net of $11,476 and $13,077 at September 30, 2023 and December 31, 2022, respectively
[2]	Includes related party operating lease right-of-use assets, net of $13,077 at December 31, 2022
[3]	Includes amounts due to related party of $112,740 and $102,113 at September 30, 2023 and December 31, 2022, respectively
[4]	Includes amounts due to related party of $102,113 and $88,799 at December 31, 2022 and 2021, respectively
[5]	Includes related party current portion of operating lease liabilities of $1,912 and $1,836 at September 30, 2023 and December 31, 2022, respectively
[6]	Includes related party current portion of operating lease liabilities of $1,836 at December 31, 2022
[7]	Includes related party long-term operating lease liabilities of $9,994 and $11,631 at September 30, 2023 and December 31, 2022, respectively
[8]	Includes related party long-term operating lease liabilities of $11,631 at December 31, 2022

Business Combinations, Unaudited Pro forma Consolidated Financial Information (FY) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Unaudited Pro forma Consolidated Financial Information [Abstract]
Revenue	$ 1,149,670	$ 1,033,187	$ 951,182
Net income	2,589	1,289	22,381
Revenues	22,900	55,700	$ 63,100
Liabilities recorded amount related to unwind agreements	$ 0	$ 0

Net Loss Per Share - Antidilutive Securities (Q3) (Details)	9 Months Ended
	Sep. 30, 2023 shares
Series A Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share (in shares)	6,651,610
Common Class B
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share (in shares)	25,109,551
Class B Prefunded Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share (in shares)	3,000,245
Public and Private Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earnings per share (in shares)	14,450,883

Subsequent Events (FY)	12 Months Ended
Subsequent Events (FY)	Dec. 31, 2022
Subsequent Events [Abstract]
Subsequent Events and Other Matters	19. Subsequent Events The Company has evaluated subsequent events through April 27, 2023, the date these consolidated financial statements were available to be issued and has determined that the following subsequent event requires disclosure in the consolidated financial statements. On February 28, 2023, AON entered into a term sheet with a third-party institutional investor contemplating, on a non-binding basis, an aggregate investment by such investor of at least $65.0 million in the form of newly issued convertible preferred securities, to be consummated concurrently with the closing of the DTOC Transaction. In connection with the reissuance of the consolidated financial statements, the Company has evaluated subsequent events through the date the consolidated financial statements were available to be reissued.

Variable Interest Entities - Schedule of Assets and Liabilities (Q3) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Assets
Cash and cash equivalents	$ 51,653	$ 26,926	$ 27,354
Inventories	37,844	36,476	34,529
Goodwill and intangibles, net	1,230	1,230	1,112
Total assets	394,014	326,228	248,298
Liabilities
Other long-term liabilities	10,333	5,749	5,717
Total liabilities	300,923	264,212	$ 188,754
Variable Interest Entity, Primary Beneficiary
Assets
Cash and cash equivalents	33,083	26,844
Accounts receivable	141,039	136,098
Inventories	37,844	36,476
Prepaid expenses and other current assets	869	846
Goodwill and intangibles, net	180	180
Other receivables	36,294	28,139
Other assets	2,014	1,489
Total assets	251,323	230,072
Liabilities
Accounts payable	114,779	102,783
Accrued compensation and benefits	22,747	6,021
Accrued other	16,038	15,926
Other long-term liabilities	137	452
Due to AON LLC and subsidiaries, net	134,344	128,204
Total liabilities	$ 288,045	$ 253,386

Business Combinations, 2020 Acquisitions (FY) (Details) - Asset Purchase Agreements with Six Oncology Practices [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) OncologyPractice
Asset Acquisitions [Abstract]
Number of oncology practices acquired \| OncologyPractice	6
Percentage of assets acquired	100.00%
Purchase Consideration [Abstract]
Cash transferred upon closing	$ 435
Issuance of note payable	621
Non-cash settlement	654
Total consideration transferred	1,710
Net Assets Acquired [Abstract]
Inventories	834
Property and equipment	360
Prepaids	16
Total net assets acquired	1,210
Amount assigned to goodwill	$ 500

Related Parties - Notes Receivable (Q3) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Jan. 24, 2022	Dec. 31, 2021	May 22, 2020	May 01, 2020	Jun. 01, 2019	May 01, 2019
Related Party Transaction [Line Items]
Total notes receivables	$ 3,134	$ 3,873
Less: Current portion of notes receivable	(1,630)	(1,797)		$ (1,812)
Notes receivable - related parties	1,504	2,076		$ 3,151
Note 2
Related Party Transaction [Line Items]
Total notes receivables	1,027	1,057
Original Principal								$ 5,355
Note 3
Related Party Transaction [Line Items]
Total notes receivables	42	119
Original Principal							$ 491
Note 6
Related Party Transaction [Line Items]
Total notes receivables	0	351
Original Principal					$ 1,111
Note 8
Related Party Transaction [Line Items]
Total notes receivables	2,065	2,221
Original Principal						$ 2,816
Note 9
Related Party Transaction [Line Items]
Total notes receivables	$ 0	$ 125
Original Principal			$ 125

Leases, Measurement of Lease Liabilities (FY) (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash Paid for Amounts Included in the Measurement of Lease Liabilities [Abstract]
Operating cash flows from operating leases	$ 7,678	$ 9,788	$ 12,590
Operating cash flows from finance leases	79	60	79
Financing cash flows from finance leases	387	321	426	$ 205	$ 0
ROU assets obtained in exchange for new operating lease liabilities	$ 9,862	$ 9,771	9,811
Total rent expense			$ 16,200	$ 11,300

Variable Interest Entities (FY) (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Carrying Amount of Assets and Liabilities

The assets of AON Partners, Partners of Maryland, AON Central Services, and MIBA as of September 30, 2023 and December 31, 2022, are as follows:

	As of September 30, 2023	As of December 31, 2022
Assets
Cash and cash equivalents	$33,083	$26,844
Accounts receivable	141,039	136,098
Inventories	37,844	36,476
Prepaid expenses and other current assets	869	846
Goodwill and intangibles, net	180	180
Other receivables	36,294	28,139
Other assets	2,014	1,489
Total assets	$251,323	$230,072

The liabilities of AON Partners, Partners of Maryland, AON Central Services, and MIBA as of September 30, 2023 and December 31, 2022, are as follows:

	As of September 30, 2023	As of December 31, 2022
Liabilities
Accounts payable	$114,779	$102,783
Accrued compensation and benefits	22,747	6,021
Accrued other	16,038	15,926
Other long-term liabilities	137	452
Due to AON LLC and subsidiaries, net	134,344	128,204
Total liabilities	$288,045	$253,386

The assets of AON Partners and Partners of Maryland as of December 31, 2022 and 2021, are as follows:

	As of December 31,
Assets	2022	2021
Cash and cash equivalents	$26,844	$24,074
Accounts receivable	136,098	111,183
Inventories	36,476	34,529
Property and equipment, net	—	108
Prepaid expenses and other current assets	846	374
Goodwill and intangibles, net	180	180
Other receivables	28,139	24,950
Other assets	1,489	1,241
Total assets	$230,072	$196,639

The liabilities of AON Partners and Partners of Maryland as of December 31, 2022 and 2021, are as follows:

	As of December 31,
Liabilities	2022	2021
Accounts payable	$102,783	$89,275
Accrued compensation and benefits	6,021	6,504
Accrued other	15,926	9,346
Medicare advance payment	—	3,742
Other long-term liabilities	452	81
Due to AON and subsidiaries, net	128,204	102,090
Total liabilities	$253,386	$211,038

Tabular disclosure of the significant judgments and assumptions made in determining whether a variable interest (as defined) held by the entity requires the variable interest entity (VIE) (as defined) to be consolidated and (or) disclose information about its involvement with the VIE, individually or in aggregate (as applicable); the nature of restrictions, if any, on the consolidated VIE's assets and on the settlement of its liabilities reported by an entity in its statement of financial position, including the carrying amounts of such assets and liabilities; the nature of, and changes in, the risks associated with involvement in the VIE; how involvement with the VIE affects the entity's financial position, financial performance, and cash flows; the lack of recourse if creditors (or beneficial interest holders) of the consolidated VIE have no recourse to the general credit of the primary beneficiary (if applicable); the terms of arrangements, giving consideration to both explicit arrangements and implicit variable interests, if any, that could require the entity to provide financial support to the VIE, including events or circumstances that could expose the entity to a loss; the methodology used by the entity for determining whether or not it is the primary beneficiary of the variable interest entity; the significant factors considered and judgments made in determining that the power to direct the activities of a VIE that most significantly impact the VIE's economic performance are shared (as defined); the carrying amounts and classification of assets and liabilities of the VIE included in the statement of financial position; the entity's maximum exposure to loss, if any, as a result of its involvement with the VIE, including how the maximum exposure is determined and significant sources of the entity's exposure to the VIE; a comparison of the carrying amounts of the assets and liabilities and the entity's maximum exposure to loss; information about any liquidity arrangements, guarantees, and (or) other commitments by third parties that may affect the fair value or risk of the entity's variable interest in the VIE; whether or not the entity has provided financial support or other support (explicitly or implicitly) to the VIE that it was not previously contractually required to provide or whether the entity intends to provide that support, including the type and amount of the support and the primary reasons for providing the support; and supplemental information the entity determines necessary to provide.

Long-term Debt (FY) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Long-term Debt [Abstract]
Total	$ 81,250	$ 81,250	$ 65,000
Unamortized debt issuance costs		(949)	(1,306)
Total debt	$ 80,425	80,301	63,694
PNC Loan Facility [Member]
Long-term Debt [Abstract]
Total		$ 81,250	$ 65,000

Other Receivables (FY) (Tables)

12 Months Ended

Dec. 31, 2022

Other Receivables [Abstract]

Other Receivables

Other receivables consisted of the following at December 31, 2022 and 2021:

	As of December 31,
	2022	2021
Rebates receivable	$27,955	$24,950
Other	246	128
Total other receivables	$28,201	$25,078

Equity - Schedule of Changes in Units (Q3) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Common Class A
Reverse Recapitalization, Change In Value Of Units [Roll Forward]
Beginning of Period	$ 7,725	$ 7,725	$ 7,725	$ 7,725	$ 7,725
Issuance of Units	0	0	0	0
Impact of the Reverse Recapitalization	(7,725)	0	(7,725)	0
End of Period	$ 0	$ 7,725	$ 0	$ 7,725	$ 7,725
Reverse Recapitalization, Change In Units [Roll Forward]
Beginning balance (in units)	19,495,376	19,495,376	19,495,376	19,495,376	19,495,376
Issuance of units (in units)	0	0	0	0
Impact of the Reverse Recapitalization (in units)	(19,495,376)	0	(19,495,376)	0
Ending balance (in units)	0	19,495,376	0	19,495,376	19,495,376
Common Class A-1
Reverse Recapitalization, Change In Value Of Units [Roll Forward]
Beginning of Period	$ 31,040	$ 28,500	$ 28,500	$ 28,500	$ 28,500
Issuance of Units	7,185	0	9,725	0
Impact of the Reverse Recapitalization	(38,225)	0	(38,225)	0
End of Period	$ 0	$ 28,500	$ 0	$ 28,500	$ 28,500
Reverse Recapitalization, Change In Units [Roll Forward]
Beginning balance (in units)	2,281,696	1,842,520	1,842,520	1,842,520	1,842,520
Issuance of units (in units)	718,549		1,157,725
Impact of the Reverse Recapitalization (in units)	(3,000,245)		(3,000,245)
Ending balance (in units)	0	1,842,520	0	1,842,520	1,842,520
Common Class B
Reverse Recapitalization, Change In Value Of Units [Roll Forward]
Beginning of Period	$ 80	$ 90	$ 80	$ 80	$ 80
Issuance of Units	10	5	10	15
Impact of the Reverse Recapitalization	(90)	0	(90)
End of Period	$ 0	$ 95	$ 0	$ 95	$ 80
Reverse Recapitalization, Change In Units [Roll Forward]
Beginning balance (in units)	4,703,628	4,703,628	4,703,628	4,703,628	4,703,628
Issuance of units (in units)	910,548	0	910,548	0
Impact of the Reverse Recapitalization (in units)	(5,614,176)	0	(5,614,176)	0
Ending balance (in units)	0	4,703,628	0	4,703,628	4,703,628

Business (Q3) (Tables)

9 Months Ended

Sep. 30, 2023

Schedule of Affiliation Agreements

During the nine months ended September 30, 2023 and 2022, the Company entered into affiliation agreements with or acquired the following oncology practices.

Nine Months Ended September 30, 2022			Nine Months Ended September 30, 2023
State			State
Arizona			Texas^(a)
Georgia^(a)			Florida^(a)
Louisiana^(a)			Arkansas^(a)
Georgia^(a)
Georgia^(a)
Georgia^(a)

(a)	The Company entered into affiliation agreements with the physicians for these respective practices. The Company evaluated each of the affiliation agreements and determined that the transactions did not represent a business combination.

Business (FY) (Details)

9 Months Ended

12 Months Ended

Sep. 30, 2023

practice

Dec. 31, 2022

OncologyPractice

Dec. 31, 2021

Dec. 31, 2020

Subsidiaries in Consolidation [Abstract]

Number of oncology practices

North Carolina [Member] | Location 12 [Member]

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Maryland [Member] | Location 13 [Member]

Apr. 01, 2020

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Maryland [Member] | Location 18 [Member]

May 01, 2020

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Virginia [Member] | Location 14 [Member]

Mar. 01, 2021

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Michigan [Member] | Location 15 [Member]

May 01, 2020

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Washington [Member] | Location 16 [Member]

Jul. 01, 2020

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Washington [Member] | Location 20 [Member]

Aug. 01, 2020

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Arizona [Member] | Location 19 [Member]

May 01, 2021

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Arizona [Member] | Location 22 [Member]

Apr. 01, 2021

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Arizona [Member] | Location 23 [Member]

Nov. 01, 2021

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Georgia [Member] | Location 21 [Member]

Jan. 01, 2022

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Georgia [Member] | Location 24 [Member]

^[1]

Aug. 01, 2021

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Georgia [Member] | Location 26 [Member]

^[1]

Jan. 01, 2022

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Georgia [Member] | Location 27 [Member]

^[1]

Apr. 05, 2022

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Georgia [Member] | Location 28 [Member]

^[1]

May 01, 2022

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Louisiana [Member] | Location 25 [Member]

^[1]

Sep. 20, 2022

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Georgia and South Carolina [Member] | Location 17 [Member]

^[1]

Jan. 17, 2022

Additional Purchases of Physician Practices in Addition to Seeking Out New Affiliation Relationships [Abstract]

Earnings (Loss) Per Share [Abstract]

Sep. 01, 2020

[1]	The Company entered into affiliation agreements with the physicians for these respective practices. The Company evaluated each of the affiliation agreements and determined that the transactions did not represent a business combination.

Net Loss Per Share (Q3)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Net Loss Per Share

13. Net Loss Per Share

The following table sets forth the computation of basic and diluted net loss per share of Class A Common Stock and represents the period from September 21, 2023 to September 30, 2023, the period where the Company had Class A and Class B common stock outstanding. Class B Common Stock does not have economic rights in AON Inc., including rights to dividends or distributions upon liquidation, and as a result, is not considered a participating security for basic and diluted loss per share. As such, basic and diluted loss per share of Class B Common Stock has not been presented. Series A Preferred Stock are considered participating securities for basic and diluted loss per share, but do not participate in losses. As such, basic and diluted loss per share is computed using the two-class method. For additional information, see Notes 1 and 2.

Basic loss per share is based on the weighted-average number of shares of Class A Common Stock outstanding during the period. Diluted loss per share is based on the weighted-average number of shares of Class A Common Stock used for the basic loss per share calculation, adjusted for the dilutive effect of Public and Private Warrants and Sponsor Earnouts, if any, using the “treasury stock” method and the convertible Series A Preferred Stock, Class B Common Stock, and Class B Prefunded Warrants, if any, using the “if-converted” method. Net loss for diluted loss per share is adjusted for the Company’s share of AON LLC’s consolidated net loss, net of AON Inc. taxes, after giving effect to Class B Common Stock and Class B Prefunded Warrants that are exchanged into potential shares of Class A Common Stock, Public and Private Warrants that are liability classified, and Series A Preferred Stock that accrue dividends, to the extent it is dilutive.

Net loss attributable to Class A Common Stockholders for basic and diluted loss per share			$ (1,791,768)
Series A Deemed Dividend			(2,089,000)
Series A Preferred Cumulative Dividends			(133,032)
Undistributed Net Loss attributable to Class A Common Stockholders			$ (4,013,000)

Weighted-average shares for basic and diluted loss per share			6,614,229
Basic & Diluted loss per share of Class A Common Stock			$ (0.61)

The following table details the securities that have been excluded from the calculation of weighted-average shares for diluted loss per share for the period presented as they were anti-dilutive. Note that the Sponsor Earnouts are excluded from the calculation of weighted-average shares for diluted loss per share as the contingency had not been met as of the period end.

Series A Preferred Stock			6,651,610
Class B Common Stock			25,109,551
Class B Prefunded Warrants			3,000,245
Public and Private Warrants			14,450,883

18. Earnings (Loss) Per Share

The Company recast Historical AON LLC equity as AON Inc. common equity for all periods prior to the Reverse Recapitalization, refer to Note 2. However, as 100% of the net income (loss) of AON LLC prior to the Reverse Recapitalization is attributable to the Legacy AON Shareholders, basic and diluted earnings (loss) per share is zero for years ended December 31, 2022, 2021, and 2020.

Leases, Related Party (FY) (Details)
$ in Thousands

12 Months Ended

Dec. 31, 2022

USD ($)

Facility

Sep. 30, 2023

USD ($)

Dec. 31, 2021

USD ($)

^[2]

Related Party Leases [Abstract]

Number of lease facilities controlled by related parties | Facility

$ 43,724

^[1],[2]

$ 46,138

^[1]

$ 0

46,401

49,384

Related Party Leases [Abstract]

13,077

$ 11,476

$ 13,500

[1]	Includes related party operating right-of-use assets, net of $11,476 and $13,077 at September 30, 2023 and December 31, 2022, respectively
[2]	Includes related party operating lease right-of-use assets, net of $13,077 at December 31, 2022

Supplemental Condensed Balance Sheet Information - Schedule of Other Receivables (Q3) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Business [Abstract]
Rebates receivable	$ 36,556	$ 27,955
Other	191	246
Total other receivables	$ 36,747	$ 28,201	$ 25,078

Condensed Consolidated Balance Sheets (Q3) - USD ($)
$ in Thousands

Sep. 30, 2023

Dec. 31, 2022

Current assets

Short-term marketable securities

$ 51,653

$ 26,926

26,034

9,851

141,039

136,098

37,844

36,476

36,747

28,201

Current portion of notes receivable - related parties

3,445

2,670

1,630

1,797

Total current assets

298,392

242,019

36,240

31,980

Notes receivable - related parties

^[1]

46,138

43,724

^[2]

1,504

2,076

7,055

5,199

1,230

Deferred tax asset, net

3,455

394,014

326,228

Current liabilities

^[3]

120,383

106,495

^[4]

16,210

7,466

22,977

17,800

Excise taxes payable

1,211

Total current liabilities

^[5]

7,123

9,177

^[6]

167,904

140,938

Long-term debt, net

80,425

80,301

^[7]

42,261

37,224

^[8]

10,333

5,749

Series A convertible preferred stock; $0.0001 par value; 7,500,000 shares authorized; 6,651,610 issued and outstanding at September 30, 2023, with an aggregate liquidation preference of $66,649,130 at September 30, 2023.

300,923

264,212

Mezzanine equity

64,986

Redeemable noncontrolling interest

369,329

Additional paid-in capital

Accumulated other comprehensive income (loss)

(117)

Retained earnings (deficit)

(341,357)

25,828

Total stockholders' equity

(341,332)

Total members' equity

62,016

Noncontrolling interest

108

Total liabilities and members' equity

394,014

326,228

Capital Unit, Class A

7,725

Capital Unit, Class A-1

28,500

Capital Unit, Class B

Common Class A

Common stock, value

7,725

Common Class B

Common stock, value

$ 3

Schedule of Reverse Recapitalization, Ownership Summary

$ 80

[1]	Includes related party operating right-of-use assets, net of $11,476 and $13,077 at September 30, 2023 and December 31, 2022, respectively
[2]	Includes related party operating lease right-of-use assets, net of $13,077 at December 31, 2022
[3]	Includes amounts due to related party of $112,740 and $102,113 at September 30, 2023 and December 31, 2022, respectively
[4]	Includes amounts due to related party of $102,113 and $88,799 at December 31, 2022 and 2021, respectively
[5]	Includes related party current portion of operating lease liabilities of $1,912 and $1,836 at September 30, 2023 and December 31, 2022, respectively
[6]	Includes related party current portion of operating lease liabilities of $1,836 at December 31, 2022
[7]	Includes related party long-term operating lease liabilities of $9,994 and $11,631 at September 30, 2023 and December 31, 2022, respectively
[8]	Includes related party long-term operating lease liabilities of $11,631 at December 31, 2022

Redeemable Noncontrolling Interest - Narrative (Q3) (Details) - USD ($) $ in Thousands		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Sep. 20, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
Noncontrolling Interest [Line Items]
Redemption ratio		1
Number of days after redemption notice date that redemption must be settled		10 years
Redemption value of noncontrolling interest	$ 369,300	$ 369,300
Excess redeemable noncontrolling interest over carrying amount	344,300	344,300
Fair value adjustment to redeemable noncontrolling interest	344,371
Additional Paid in Capital
Noncontrolling Interest [Line Items]
Fair value adjustment to redeemable noncontrolling interest	17,602	17,600
Retained Earnings (Deficit)
Noncontrolling Interest [Line Items]
Fair value adjustment to redeemable noncontrolling interest	$ 326,769	$ 326,700
Common Class A
Noncontrolling Interest [Line Items]
Common unit, units outstanding (in units)					19,495,376	19,495,376
Common stock, shares outstanding (in shares)	9,453,604	9,453,604
Stockholders' equity, conversion, threshold volume weighted average price period		5 days
Legacy AON Shareholders \| AON LLC
Noncontrolling Interest [Line Items]
Common unit, units outstanding (in units)	28,109,796	28,109,796
Allocation of income to controlling and noncontrolling interests	81.00%	67.90%	100.00%	100.00%
Common stock, shares outstanding (in shares)	25,109,551	25,109,551
Class of warrant outstanding (in warrants)	3,000,245	3,000,245
LLC ownership threshold, percentage	50.00%	50.00%
AON Inc. \| AON LLC
Noncontrolling Interest [Line Items]
Allocation of income to controlling and noncontrolling interests	19.00%

Redeemable Noncontrolling Interest (Q3) (Tables)

9 Months Ended

Sep. 30, 2023

Noncontrolling Interest [Abstract]

	Period beginning September 20, 2023 and ending September 30, 2023
		AON LLC Units
	AON Inc.	Legacy AON Shareholders	Total
Beginning of Period	—	—	—
Common Units Issued⁽¹⁾	6,614,229	28,109,796	34,724,025
Series A Preferred Units Issued	6,651,610	—	6,651,610
Total Units Issued	13,265,839	28,109,796	41,375,635
End of Period	13,265,839	28,109,796	41,375,635
Allocation of income to controlling and noncontrolling interests	32.1%	67.9%	100%
Allocation of losses to controlling and noncontrolling interests⁽²⁾	19.0%	81.0%	100%

(1)	The 6,614,229 of AON Inc. Common Units excludes 2,839,375 units, which is equivalent to the number of Sponsor Earnout Shares, that do not participate in profits and losses and are not included in the controlling interest percentage.

(2)

Summary of Significant Accounting Policies and Basis of Presentation (FY) (Policies)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Summary of Significant Accounting Policies and Basis of Presentation [Abstract]

Basis of Presentation

The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The consolidated financial statements include the accounts of the Company, its wholly owned subsidiary American Oncology Network, LLC, American Oncology Management Company, LLC (“AOMC”), and its consolidated variable interest entities (“VIEs”), American Oncology Partners, P.A. (“AON Partners”), American Oncology Partners of Maryland, P.A. (“Partners of Maryland”) and AON Central Services, LLC (“Central Services”). AON Central Services, LLC was established during 2022; however, as of December 31, 2022, it had no activity.

For the year ended December 31, 2020, 2021, and 2022, these consolidated financial statements present the consolidated results of operations, comprehensive income (loss), cash flows and changes in equity of AON LLC and its wholly-owned subsidiaries and variable interest entities. The consolidated balance sheet as of December 31, 2022 and December 31, 2021, presents the financial condition of AON LLC and its wholly-owned subsidiaries and variable interest entities. All significant intercompany accounts, related-party balances and transactions between the entities have been eliminated in consolidation.

The Company accounts for American Oncology Network, LLC, AON Partners, and Partners of Maryland in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 810, Consolidations. The Company determines whether it has a controlling financial interest in an entity by first evaluating whether the entity is a VIE. A VIE is broadly defined as an entity that has any of the following three characteristics: (i) the equity investment at risk is insufficient to finance the entity’s activities without additional subordinated financial support; (ii) substantially all of the entity’s activities either involve or are conducted on behalf of an investor that has disproportionately few voting rights; or (iii) the equity investors as a group lack any of the following, the power through voting or similar rights to direct the activities of the entity that most significantly impact the entity’s economic performance, the obligation to absorb the expected losses of the entity, or the right to receive the expected residual returns of the entity. The Company consolidates a VIE if it has both the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and an obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. Management performs ongoing reassessments of whether changes in the facts and circumstances regarding the Company’s involvement with a VIE will cause the consolidation conclusion to change. Changes in consolidation status are applied prospectively, if any.

AON LLC has contractual relationships with AON Partners and Partners of Maryland and the physician owners through management service agreements (“MSAs”) and other contractual agreements to provide all practice management services outside of medical services provided by the physicians. In addition, despite not being required by the contractual relationships, AON LLC regularly provides funding to support AON Partners and Partners of Maryland’s operations and acquisitions of physician practices. The Company has concluded that AON Partners and Partners of Maryland are both VIEs in which AON LLC has the characteristics of a controlling financial interest and is deemed to be the primary beneficiary. The variable interest subjects the Company to all potential losses in the entities and, therefore, requires AON LLC, and in turn the Company, to consolidate the results of AON Partners and Partners of Maryland in its consolidated financial statements. As noted above, Central Services is also a VIE; however, there was no activity during 2022. Refer to Note 4 for further information on the VIEs.

Accounting Estimates and Assumptions

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting periods. Significant estimates and assumptions are involved in the calculation of the Company’s allowance for contractual adjustments and allowances for uncollectible on accounts receivable, liabilities for provider compensation, and accrued insurance claim reserves. Actual results could differ from those estimates.

Segments

Revenue Recognition

Additionally, the Company does not expect to recognize material revenue in the future related to performance obligations that are unsatisfied (or partially satisfied) as of December 31, 2022 and 2021. Approximately $818.5 million, $683.0 million, and $542.0 million of the Company’s revenues are generated from services performed during patient visits with the remainder primarily generated from shipments of pharmacy prescriptions for the years ended December 31, 2022, 2021, and 2020, respectively.

As services are performed and prescriptions are shipped, billing occurs for services rendered and prescriptions shipped less discounts provided to uninsured patients and contractual adjustments to third-party payors based upon prospectively determined rates and discounted charges. Payment is requested at the time of service for self-paying patients and for patients covered by third-party payors that are responsible for paying deductibles and coinsurance.

The Company monitors revenue and receivables to prepare estimated contractual allowances for the anticipated differences between billed and reimbursed amounts. Payments from third-party payors and Government programs including Medicare and Medicaid may be subject to audit and other retrospective adjustments. Such amounts are considered on an estimated basis when net patient revenue is recorded and are adjusted as final adjustments are determined. For the years ended December 31, 2022, 2021, and 2020, such resulting historic adjustments have been immaterial to the consolidated financial statements.

The Company uses the cost-to-cost measure of progress for the Company’s contract because it best depicts the transfer of control to the customer as the performance obligation is fulfilled. For this method, the Company compares the contract costs incurred to date to the estimated total contract costs through completion. As part of the client proposal and contract negotiation process, the Company develops a detailed project budget for the direct costs and reimbursable costs based on the scope of the work, the complexity of the study, the geographical location involved and the Company’s historical experience. The estimated total contract costs at the project level are reviewed and revised periodically throughout the life of the contract, with adjustments to revenue resulting from such revisions being recorded on a cumulative basis in the period in which the revisions are identified. Contract costs consist primarily of direct labor and other reimbursable project-related costs such as travel, third-party vendor costs and investigator fees. The Company establishes pricing based on the Company’s internal pricing guidelines, discount agreements, if any, and negotiations with the client. The transaction price is the contractually defined amount. For the year ended December 31, 2022, the Company recognized revenue of $4.3 million related to the clinical trial which is included within other revenue.

In March 2020, the World Health Organization determined the resulting outbreak of COVID-19, the disease caused by this novel coronavirus, to be a pandemic. The pandemic is disrupting supply chains worldwide as national and local governments implement measures intended to slow the spread of COVID-19, with production and sales across a range of industries impacted in different ways.

On March 27, 2020, the United States enacted the Coronavirus Aid, Relief and Economic Security Act, or CARES Act. The CARES Act is an emergency economic stimulus package that includes spending and tax breaks to strengthen the United States economy and fund a nationwide effort to curtail the effect of COVID-19. The CARES Act provides sweeping tax changes in response to the COVID-19 pandemic, some of the more significant provisions include removal of certain limitations on utilization of net operating losses, increasing the loss carryback period for certain losses to five years, increasing the ability to deduct interest expense, and deferring social security payments, as well as amending certain provisions of the previously enacted Tax Cuts and Jobs Act.

In April 2020, the Company received approximately $24.0 million of cash from government stimulus programs designed to assist small businesses during the pandemic. Of this amount, $17.2 million in advances included on the Consolidated Balance Sheet as of December 31, 2020, were received under the Centers for Medicare & Medicaid Services (CMS) accelerated and advance payment program which is for services to be rendered and reimbursed under Medicare programs. In October 2020, as determined by the Continuing Appropriations Act, 2021 and Other Extensions Act, the recoupment period would begin one year after the date the advance payment was received, therefore recoupment began in April 2021. At December 31, 2022 and 2021, the outstanding liability was $0 and $3.7 million, respectively. Revenue recognized in the reporting period that was included in the Medicare advance payment balance at January 1, 2022 and January 1, 2021 was $3.7 million and $13.5 million, respectively. The remaining $6.8 million of the $24.0 million received was in the form of a grant from the Department of Health and Human Services and does not require repayment. As an accounting policy election, the Company utilized ASC 958 by analogy to recognize funds received under the CARES Act from the Provider Relief Fund as revenue, given no direct authoritative guidance is available to for-profit organizations to recognize revenue for government contributions and grants.

The Company has a system and estimation process for recording Medicare net patient service revenue and estimated recoupments as it relates to value-based care (“VBC”) revenue included in patient service revenue on the Consolidated Statements of Operations and Comprehensive Income (Loss). The Company’s VBC revenue is primarily generated through its participation in the CMS Oncology Care Model (“OCM”) which is an episode-based payment model to promote high-quality cancer care. Participants enter six-month episode periods, and the Company bills a monthly fee during the six-month period based on a fixed rate per participant per month and the total number of participants. Certain quality and compliance metrics are tracked as part of the program and submitted to CMS at the end of the episode period which may result in recoupment of funds. The Company estimates the recoupment amount by developing a recoupment percentage for each period based on historical known recoupment from CMS and applies the recoupment percentage against total fees for the period. Based on the estimate, the Company accrues a liability representing the expected final recoupments based on historical settlement trends.

Short-term Marketable Securities

Investments in marketable securities consist of corporate bonds and U.S. Treasury securities.

Short-term Marketable Securities

Investments in marketable securities consist of corporate bonds and U.S. Treasury securities. Management determines the appropriate classification of investments at the time of purchase and reevaluates such determination

at each balance sheet date. Marketable securities are classified as available-for-sale and are carried at fair value in the Consolidated Balance Sheets. The marketable securities are classified as short- term based on management’s intent to convert such securities within one year and the ability to convert them within two to three days.

The Company evaluates its investments to assess whether those with unrealized loss positions were other than temporarily impaired. Impairments were considered to be other than temporary if they were related to deterioration in credit risk or if it is likely the Company will sell the securities before the recovery of their cost basis. Realized gains and losses and declines in value judged to be other than temporary were determined based on the specific identification method and reported in Interest income in the Consolidated Statements of Operations and Comprehensive Income (Loss).

Cost of Revenue

Cost of services primarily includes chemotherapy drug costs, clinician salaries and benefits, medical supplies and clinical occupancy costs. Clinicians include oncologists, advanced practice providers such as physician assistants and nurse practitioners, and registered nurses. Specialty pharmacy costs primarily include the cost of oral medications dispensed from the specialty pharmacy including overhead costs for running a free-standing pharmacy and shipping costs to patients.

Business Combinations

The Company evaluates acquired practices in accordance with ASU 2017-01, Business Combinations (Topic 805) — Clarifying the Definition of a Business. This standard clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions or disposals of assets or businesses. Because substantially all of the value of each acquired practice did not relate to a similar group of assets and as each acquired practice contained both inputs and processes necessary to provide economic benefits to the Company, it was determined that each acquisition represents a business combination. Therefore, the transactions have been accounted for using the acquisition method of accounting, which requires, with limited exceptions, that assets acquired, and liabilities assumed be recognized at their estimated fair values as of the acquisition date. Any excess of the consideration transferred over the estimated fair values of the net assets acquired is recorded as goodwill. Transaction costs related to business combinations are expensed in the period in which they are incurred.

Cash and Cash Equivalents

The Company considers all highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Cash and cash equivalents include cash or deposits with financial institutions and deposits in highly liquid money market securities. Deposits with financial institutions are insured by the Federal Deposit Insurance Corporation up to certain defined limits. Bank deposits at times may exceed federally insured limits. The Company has not experienced any losses in these accounts.

Restricted Cash

The Company maintains certain cash balances restricted as to withdrawal or use and presented separately from Cash and cash equivalents on the Consolidated Balance Sheets. Restricted cash includes amounts held as collateral related to the Company’s PNC Loan Facility (Note 11).

	As of December 31,
	2022	2021
Cash and cash equivalents	$26,926	$27,354
Restricted cash	—	5,000
Total cash, cash equivalents and restricted cash shown in the statements of cash flow	$26,926	$32,354

Accounts Receivable

Accounts receivable from patients are carried at the original charge for the services provided, and an adjustment is made to the receivable in a contra account based on the historical collection rate for the provider and payor

combination. This adjustment takes into consideration any allowance for doubtful accounts. Management determines the allowance for uncollectible accounts based on historical experience. Concentrations of accounts receivable, net of allowances for contractual discounts and doubtful accounts, as of December 31, 2022 and 2021, are as follows:

	As of December 31,
	2022	2021
Medicare	25%	27%
Managed Medicare	25%	21%
Other Commercial	17%	17%
BCBS	17%	16%
Managed Medicaid	8%	12%
Other	8%	7%
	100%	100%

As of December 31, 2022, December 31, 2021, and January 1, 2021, the accounts receivable, net balances were $136.1 million, $111.2 million, and $80.4 million, respectively.

Inventories, consisting primarily of pharmaceuticals finished goods, are valued at the lower of cost or net realizable value, with cost being determined on a first-in, first-out basis. Obsolescence for inventories is estimated based on expiration dates and slow-moving inventory. No obsolescence allowances have been recorded as of December 31, 2022 and 2021. If the Company determines that an item is obsolete, or the expected net realizable value upon sale is lower than the currently recorded cost, a write-down is recorded and charged to cost of revenue to reduce the inventory to its net realizable value and a new cost basis is established. The majority of the Company’s inventories are purchased from a related party (See Note 14).

Other Receivables

Other receivables consist primarily of rebates on drug purchases made in the current period which are offered as an incentive by the distributor and/or manufacturer and are not yet paid as of year-end.

Property and Equipment

Leasehold improvements			1 – 15 years
Furniture, fixtures and equipment			7 years
Medical equipment			5 – 10 years
Computer equipment			5 years
Signs			7 years
Automobiles			5 years
Software			7 years

Leasehold improvements are amortized using the straight-line method over the shorter of their estimated useful lives or the term of the related lease, which may include one or more option renewal periods. Maintenance and repairs that do not improve service potential or extend economic life are expensed as incurred. Expenditures for major improvements and additions are capitalized. Long-lived assets to be held and used are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset group may not be recoverable. In assessing long-lived assets for impairment, assets are grouped with other assets and liabilities at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities. Recoverability is measured by a comparison of the carrying amount of an asset group to the undiscounted future net cash flows expected to be generated by the asset group. If estimated future undiscounted cash flows are not sufficient to recover the carrying value of the assets, impairment is measured by comparing the carrying amount of the assets to the estimated fair value, obtained through appraisal or market quotations, or discounted future net cash flow estimates. The Company did not recognize any long-lived asset impairments during 2022, 2021, and 2020.

Goodwill

Goodwill arising from business combinations represents the excess of the fair value of consideration transferred over the fair value of the identifiable net assets acquired and liabilities assumed as of the acquisition date. Goodwill amounts are not amortized, but rather tested for impairment annually, on October 1, or more often if circumstances indicate that the carrying value may not be recoverable. There was no impairment of goodwill during any of the periods presented.

Concentration of Credit Risk

Effective January 1, 2022, the Company adopted ASU 2016-02, Leases and the subsequently issued supplemental and/or clarifying ASUs known as ASC Topic 842 (collectively “ASC 842”) using the modified retrospective approach. See Recently Adopted Accounting Pronouncements below, which discusses the initial adoption of this new guidance.

The Company’s lease portfolio primarily consists of office and equipment leases for its practice facilities. The Company evaluates whether a contract is or contains a lease at contract inception. A lease exists when a contract conveys to the customer the right to control the use of identified property or equipment for a period of time in exchange for consideration. The definition of a lease embodies two conditions: 1) there is an identified asset in the contract that is land or a depreciable asset (i.e., property, plant, and equipment); and 2) the customer has the right to control the use of the identified asset. ASC 842 requires a lessee to discount its unpaid lease payments using the interest rate implicit in the lease or, if that rate cannot be readily determined, its incremental borrowing rate. As the Company’s operating leases do not generally provide an implicit rate, the incremental borrowing rate is used based on the information available at commencement date in determining the present value of lease payments. The incremental borrowing rate for a lease is the rate of interest the Company would have to pay on a collateralized basis to borrow an amount equal to the lease payments under similar terms. The lease term for all of the Company’s operating leases include the noncancellable period of the lease plus any additional periods covered by either a lessee option to extend (or not to terminate) the lease that the lessee is reasonably certain to exercise, or an option to extend (or not to terminate) the lease controlled by the lessor. Lease payments included in the measurement of the operating lease right-of-use (“ROU”) assets and lease liabilities are comprised of fixed payments (including in-substance fixed payments), variable payments that depend on an index or rate, and the exercise price of a lessee option to purchase the underlying asset if the lessee is reasonably certain to exercise.

The Company elected not to recognize operating lease ROU assets and lease liabilities for all short-term leases (leases with an initial lease term of 12 months or less). The Company recognizes the lease payments associated with short-term leases as an expense over the lease term.

The operating lease ROU assets are initially measured at cost, which comprises the initial amount of the lease liability adjusted for lease payments made at or before the lease commencement date, plus any initial direct costs incurred less any lease incentives received. The operating lease ROU assets are subsequently measured throughout the lease term at the carrying amount of the lease liability, plus initial direct costs, plus (minus) any prepaid (accrued) lease payments, less the unamortized balance of lease incentives received. Lease expense for lease payments is recognized on a straight-line basis over the lease term. The operating lease liabilities are initially measured at the present value of the unpaid lease payments at the lease commencement date.

Income Taxes

The Company accounts for its income taxes using the asset and liability method whereby deferred tax assets and liabilities are determined based on temporary differences between the basis used for financial reporting and income tax reporting purposes. Deferred income taxes are provided based on the enacted tax rates in effect at the time such temporary differences are expected to reverse. A valuation allowance is provided for deferred tax assets if it is more likely than not that the Company will not realize those tax assets through future operations.

As limited liability companies, the Company and its consolidated subsidiary are treated as partnerships for tax purposes. For these entities, income taxes are not payable or provided for, as the Company’s members are taxed individually on their interest in the Company’s taxable income. AON Partners and Partners of Maryland are both C corporations for tax reporting purposes. As such, a provision and liability for income taxes related to the results of these operations have been included in the Consolidated Statements of Operations.

Accounting for uncertainty in income taxes prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken, or expected to be taken, in a tax return.

Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and accounts receivable. Although certain cash accounts exceed the federally insured deposit amount, management has not previously experienced nonperformance by any financial institution.

Equity-Based Compensation

The Company measures the compensation cost of all equity awards at the estimated fair value of the award on the date of grant and records the related expense in the accompanying Consolidated Statements of Operations and Comprehensive Income (Loss) on a straight-line basis over the applicable service period. The Company uses an option pricing method to value its common stock. This method allocates the fair value of total equity to the various components of equity based on an estimated liquidity event. This option pricing method first values the Company at the enterprise level, and then values breakpoints based on the liquidation preferences of the Class A, Class A-1, and Class B units. An allocation of total equity (enterprise value) is then performed to the various equity components based on the relative rights and privileges of each class of equity. The Company was assisted by third-party valuation experts to apply the above models to calculate the fair value estimate. Forfeitures are accounted for as they occur.

Debt Issuance Costs

Debt issuance costs consist of legal fees and other professional services and are capitalized. Debt issuance costs are presented in the Consolidated Balance Sheets as a direct deduction from the carrying value of the associated debt liability and amortized to interest expense in the Consolidated Statements of Operations and Comprehensive Income (Loss). The costs related to the term loans are amortized using the straight-line method, which approximates the effective interest method, over the terms of the related debt. The amortization related to the debt issuance costs included in interest expense within the accompanying Consolidated Statements of Operations and Comprehensive Income (Loss) was $0.6 million in 2022, $0.4 million in 2021, and immaterial in 2020.

Offering Costs

The Company defers specific incremental costs directly attributable to proposed offerings of securities. These costs consist of legal, accounting, and other similar expenses incurred through the balance sheet date that are directly related to a potential offering. If the offering is completed, these costs will be charged against the gross proceeds of the offering. These offering costs will be allocated to the separable financial instruments issued in the transaction on a relative fair value basis of the securities issued, compared to total proceeds received. Offering costs associated with any instruments classified as liabilities will be expensed as incurred, presented as non-operating expenses in the Consolidated Statement of Operations and Comprehensive Income (Loss). At December 31, 2022, the Company had incurred approximately $0.3 million of offering costs which are included in other assets in the accompanying Consolidated Balance Sheets.

Professional Liability

The Company maintains insurance policies for exposure to professional malpractice insurance risk. The limits of malpractice insurance provide each physician/advanced practice provider with a dedicated $1.0 million limit per claim and a $3.0 million limit in the aggregate per policy period — on a first dollar basis, as no deductible applies. The policy further then extends coverage to the Company, by providing a $2.0 million limit per claim and a $4.0 million limit in the aggregate per policy period — on a first dollar basis, additionally, as no deductible applies. Reserves are established for estimates of the loss that will ultimately be incurred on claims that have been reported but not paid and claims that have been incurred but not reported. These reserves are established based on consultation with a third-party actuary. The actuarial valuations consider a number of factors, including historical claims payment patterns, changes in case reserves and the assumed rate of increase in healthcare costs. Management believes the use of actuarial methods to account for these reserves provides a consistent and effective way to measure these subjective accruals. However, due to the sensitive nature of this estimation technique, recorded reserves could differ from ultimate costs related to these claims due to changes in claims reporting, claims payment and] settlement practices and differences in assumed future cost increases. Accrued unpaid claims and expenses that are expected to be paid within the next twelve months are classified as current liabilities and included in accrued other. All other accrued unpaid claims and expenses are classified as long-term liabilities and included in other long-term liabilities. Insurance recoveries associated with the unpaid claims are classified as long-term assets included in other assets.

Fair Value of Financial Instruments

Level 1

Inputs to the valuation methodology are quoted prices (unadjusted) for an identical asset or liability in an active market.

Level 2

Level 3

Fair Value of Financial Instruments

Fair value is the price that would be received to sell an asset or paid to transfer a liability in the principal or most advantageous market in an orderly transaction between market participants on the measurement date. The carrying values of cash and cash equivalents, receivables, accounts payable, other current liabilities, and accrued interest approximate fair value due to their short-term nature.

Level 1

Inputs to the valuation methodology are quoted prices (unadjusted) for an identical asset or liability in an active market.

Level 2

Level 3

Inputs to the valuation methodology are unobservable and significant to the fair value measurement of the asset or liability.

Recently Adopted/ Issued Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

Recently Adopted Accounting Pronouncements

On January 1, 2022, the Company adopted ASU 2016-02, “Leases” (Topic 842), using the modified retrospective approach for leases that existed on January 1, 2022. ASC 842 requires lessees to recognize assets and liabilities for most leases.

The Company elected to adopt the leasing package of practical expedients, which provides for not retroactively reassessing: i) any expired or existing contracts containing leases under the new definition of a lease; ii) the lease classification for any expired or existing leases; and iii) initial direct costs for any expired or existing leases. The Company also elected to adopt practical expedients around land easements and the combination of lease and non-lease components for its real estate leases. These practical expedients were applied consistently to all applicable leases.

Upon adoption of ASC 842, the Company recorded an initial adjustment to the opening balance sheet of $44.4 million to operating ROU assets, ($1.2) million to prepaid expenses and other current assets, $8.0 million to current portion of operating lease liabilities, $38.0 million to long-term operating lease liabilities, $2.5 million in ROU assets and lease liabilities related to the Company’s finance leases; and $2.8 million to other long-term liabilities. The impact of ASC 842 was not material to the Consolidated Statement of Operations and Comprehensive Income (Loss).

In March 2020, the FASB issued ASU No. 2020-04, “Reference Rate Reform”, which provides temporary optional guidance to companies impacted by the transition away from the London Interbank Offered Rate (“LIBOR”). The guidance provides certain expedients and exceptions to applying GAAP in order to lessen the potential accounting burden when contracts, hedging relationships, and other transactions that reference LIBOR as a benchmark rate are modified. The guidance is effective as of March 12, 2020 through December 31, 2022. In February 2022, the Company amended its PNC Loan Facility whereby it is no longer referenced to LIBOR as the benchmark rate. The Company has no other contracts or transactions benchmarked to LIBOR.

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic740): Simplifying the Accounting for Income Taxes (ASU 2019-12), which simplifies the accounting for income taxes (Topic 740) by removing exceptions related to the incremental approach for intraperiod tax allocations, the requirement to recognize a deferred tax liability for certain equity method investments, the ability not to recognize a deferred tax liability for a foreign subsidiary when a foreign equity method investment becomes a subsidiary, and the general methodology for calculating income taxes in an interim period when a year-to-date loss exceeds the anticipated loss for the year. The amendments in ASU 2019-12 also simplify the accounting for income taxes by requiring that an entity recognize a franchise tax that is partially based on income as an income-based tax and account for any incremental amount

incurred as a non-income-based tax, requiring that an entity evaluate when a step up in the tax basis of goodwill should be considered part of the business combination, specifying that an entity is not required to allocate deferred tax expense to a legal entity that is not subject to tax, requiring that an entity reflect the effect of an enacted change in tax laws or rates in the interim period that includes the enactment date, and minor codification improvements for income taxes related to employee stock ownership plans. The Company adopted the provisions of ASU 2019-12 effective January 1, 2022. The adoption of this pronouncement had no material impact on the Company’s consolidated financial statements.

Recently Issued Accounting Pronouncements

In June 2016, the FASB issued ASU 2016-13, “Financial instruments — Credit Losses” (“ASU 2016-13”). ASU 2016-13 requires entities to report “expected” credit losses on financial instruments and other commitments to extend credit rather than the current “incurred loss” model. These expected credit losses for financial assets held at the reporting date are to be based on historical experience, current conditions, and reasonable and supportable forecasts. This ASU will also require enhanced disclosures relating to significant estimates and judgments used in estimating credit losses, as well as the credit quality. ASU 2016-13 is effective for the Company for annual reporting periods beginning after December 15, 2022. The Company is currently evaluating the impact that this standard will have on the consolidated financial statements.

Condensed Consolidated Statements of Operations and Comprehensive Loss (Q3) (Parenthetical) - USD ($)
$ in Thousands

3 Months Ended

9 Months Ended

Sep. 30, 2023

Sep. 30, 2022

Sep. 30, 2023

Sep. 30, 2022

^[1]

$ 310,894

$ 267,647

$ 880,827

$ 780,658

25,199

23,432

72,831

^[2]

66,155

^[2]

Related Party

271,790

236,077

777,478

682,671

$ 679

$ 655

$ 2,037

[1]	Includes related party inventory expense of $271,790 and $236,077 and $777,478 and $682,671 for the three and nine months ended September 30, 2023 and 2022, respectively.
[2]	Includes related party rent of $679 and $655 and $2,037 and $2,037 for the three and nine months ended September 30, 2023 and 2022, respectively.

The aggregate cost of goods produced and sold and services rendered during the reporting period.

Leases (FY)

12 Months Ended

Dec. 31, 2022

15. Leases

The Company currently leases office facilities and equipment for its practices under noncancelable operating and financing lease agreements expiring on various dates through 2032. Certain of the leases contain renewal options which are exercisable at the Company’s discretion. These renewal options are considered in determining the lease term if it is reasonably certain that the Company will exercise such options. Additionally, the Company leases certain other office and medical equipment under month-to-month lease agreements.

Leases for ten of the Company’s facilities are controlled by related parties as of December 31, 2022. See Note 14. As of December 31, 2022, the operating ROU assets, net and lease liabilities related to these properties were $13.1 million and $13.5 million, respectively.

Right-of-use assets and lease liabilities consist of the following at December 31, 2022:

Assets
Operating lease right-of-use assets, net			$43,724
Finance lease right-of-use assets, net (included in property and equipment, net)			1,998
Total right-of-use assets			$45,722
Liabilities
Current
Current portion of operating lease liabilities			$9,177
Current portion of finance lease liabilities (included in accrued other)			425
Long-term			9,602
Long-term operating lease liabilities			37,224
Long-term finance lease liabilities (included in other long-term liabilities)			1,619
Total lease liabilities			$48,445

The components of lease costs recognized in the Consolidated Statements of Operations and Comprehensive Income (Loss) consist of the following for the year ended December 31, 2022:

Operating lease costs			$12,465
Finance lease costs
Amortization of finance lease right-of-use assets			523
Interest on finance lease liabilities (included in interest expense)			79
Variable lease costs			2,737
Total lease costs			$15,804

	Operating Leases	Finance Leases
2023	$11,215	$491
2024	10,049	491
2025	7,762	469
2026	7,448	231
2027	6,528	166
Thereafter	11,067	429
Total lease payments	54,069	2,277
Less: amount representing interest	(7,668)	(233)
Present value of lease liabilities	46,401	2,044
Less: current portion of lease liabilities	(9,177)	(425)
Long-term lease liabilities, net of current portion	$37,224	$1,619

The weighted-average remaining lease terms as of December 31, 2022 for operating leases and finance leases are 5.68 years and 5.37 years, respectively. The weighted-average discount rates as of December 31, 2022 for operating leases and finance leases are 4.88% and 3.60%, respectively.

The cash paid for amounts included in the measurement of lease liabilities for the year ended December 31, 2022 is as follows:

Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases			$12,590
Operating cash flows from finance leases			79
Financing cash flows from finance leases			426
ROU assets obtained in exchange for new operating lease liabilities			9,811

Total rent expense prior to the adoption of ASC 842 for the years ended December 31, 2021 and 2020 was approximately $16.2 million and $11.3 million, respectively, which is primarily included in cost of revenues on the Consolidated Statements of Operations and Comprehensive Income (Loss).

Inventories (FY) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Inventory [Abstract]
Total inventories	$ 37,844	$ 36,476	$ 34,529
Intravenous Drugs [Member]
Inventory [Abstract]
Total inventories	27,508	25,674	28,897
Oral Pharmaceuticals [Member]
Inventory [Abstract]
Total inventories	$ 10,336	$ 10,802	$ 5,632

Leases, Right-of-Use Assets and Lease Liabilities (FY) (Details) - USD ($)
$ in Thousands

Sep. 30, 2023

Dec. 31, 2022

Dec. 31, 2021

Assets [Abstract]

Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]

$ 46,138

^[1]

$ 43,724

^[1],[2]

$ 0

^[2]

Operating lease right-of-use assets, net

Finance lease right-of-use assets, net (included in property and equipment, net)

2,791

$ 1,998

Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]

Property and equipment, net

Total right-of-use assets

$ 45,722

Current [Abstract]

Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]

7,123

^[3]

$ 9,177

^[3],[4]

^[4]

Current portion of operating lease liabilities

Current portion of finance lease liabilities (included in accrued other)

$ 630

$ 425

Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]

Accrued other

Total current lease liabilities

$ 9,602

Long-term [Abstract]

Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]

$ 42,261

^[5]

$ 37,224

^[5],[6]

$ 0

^[6]

Long-term operating lease liabilities

Long-term finance lease liabilities (included in other long-term liabilities)

$ 2,126

$ 1,619

Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]

Other long-term liabilities

Total lease liabilities

$ 48,445

[1]	Includes related party operating right-of-use assets, net of $11,476 and $13,077 at September 30, 2023 and December 31, 2022, respectively
[2]	Includes related party operating lease right-of-use assets, net of $13,077 at December 31, 2022
[3]	Includes related party current portion of operating lease liabilities of $1,912 and $1,836 at September 30, 2023 and December 31, 2022, respectively
[4]	Includes related party current portion of operating lease liabilities of $1,836 at December 31, 2022
[5]	Includes related party long-term operating lease liabilities of $9,994 and $11,631 at September 30, 2023 and December 31, 2022, respectively
[6]	Includes related party long-term operating lease liabilities of $11,631 at December 31, 2022

Long-term Debt (Q3)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Summary of Significant Accounting Policies and Basis of Presentation [Abstract]

Long-term Debt

8. Long-term Debt

Debt consisted of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
PNC Facility	$81,250	$81,250
Total	81,250	81,250
Unamortized debt issuance costs	(825)	(949)
Total debt	$80,425	$80,301

Credit Facilities

On April 30, 2021, the Company entered into a Loan Facility with PNC (“PNC Loan Facility”) collateralized by the Company’s assets and outstanding patient accounts receivable. The PNC Loan Facility is guaranteed on a limited basis by the Company and shareholder of AON Partners and Partners of Maryland. $34.6 million of proceeds from the PNC Loan Facility was used to pay off the Company’s previous term loans and revolver with Truist Bank. The remaining funds were made available for working capital and acquisition of additional physician practices.

The PNC Loan Facility is interest-only with total principal due at maturity on April 30, 2024. Interest originally accrued at one-month LIBOR or an alternate base rate plus 1.45%. The maximum balance of the PNC Loan Facility (“Borrowing Base”) is limited to the lesser of the Facility Limit ($65.0 million) or the fair value of the Company’s patient accounts receivable. The Company must maintain a balance of the lesser of the Borrowing Base or 65% of the Facility Limit in the first year and 75% of the Facility Limit in subsequent years (“minimum funding threshold”). The Company can repay the PNC Loan Facility up to the minimum funding threshold at any time without penalty. In accordance with the PNC Loan Facility, the Company pledged $10.0 million of collateral as restricted cash to be released quarterly in increments of $2.5 million. The restricted cash was fully released as of September 30, 2023 and December 31, 2022.

On April 30, 2021, the Company entered into a $5.0 million revolving line of credit agreement (“PNC Line of Credit”). The PNC Line of Credit has an expiration date of April 30, 2024 and originally bore interest at a rate per annum equal to the sum of the daily LIBOR rate plus 1.65% or an alternate base rate plus 0.65% and is due on the first day of each month beginning June 1, 2021. Any outstanding principal and accrued interest will be due on the expiration date. Beginning July 1, 2021, quarterly bank fees equal to 1.65% per day per annum are due in arrears and will continue on the first day of each quarter thereafter. All debt related to the PNC Line of Credit is collateralized by the Company’s assets. As of September 30, 2023 and December 31 2022, no draws had been made on the PNC Line of Credit. The Company is also subject to a 0.20% unused line fee calculated per annum on the unused balance of the PNC Line of Credit.

On July 29, 2021, the Company amended the PNC Loan Facility increasing the Facility Limit to $75.0 million. On February 14, 2022, the Company further amended the PNC Loan Facility and Line of Credit agreements. The primary changes included an increase of the Facility limit from $75.0 million to $125.0 million, an increase of the PNC Line of Credit availability from $5.0 million to $10.0 million, interest charges to be calculated based on the

Bloomberg Short-Term Bank Yield Index plus 1.65% and certain financial covenants. As part of the amendment, the Company drew an additional $16.3 million in proceeds under the Loan Facility. On August 15, 2022, the PNC Loan Facility and Line of Credit agreements were amended again to reduce the availability under the PNC Line of Credit from $10.0 million to $1.0 million.

Effective November 23, 2022, the Company entered into Waiver and Amendment No. 6 (“Waiver and Amendment”) under its PNC Loan Facility as the Company was not in compliance with the Delinquency Ratio financial covenant for the period ending October 31, 2022 and the requirement to provide certain annual financial statements. The Waiver and Amendment waives each event of default and also revised future delinquency percentages and financial statement requirements.

On June 30, 2023, the Company entered into Amendment No. 7 (“Amendment 7”) to its PNC Loan Facility which extended the maturity date from April 30, 2024 to June 30, 2026. In connection with Amendment 7, the Company paid additional debt issuance costs of $0.4 million which will be amortized over the revised remaining life of the Loan Facility. In addition, Amendment 7 revised the definition of the minimum funding threshold to limit the threshold multiplier to 65% of the Facility Limit.

The PNC Loan Facility and PNC Line of Credit nonfinancial covenants include restrictions related to unpermitted property liens and the requirement of audited financial statements. Both agreements also contain several financial covenants, including the following ratios: accounts receivable default, delinquency, dilution, days sales outstanding, leverage, and fixed charge coverage. As of September 30, 2023, the Company was in compliance with all financial and nonfinancial debt covenants as required by both loan agreements.

11. Long-term Debt

Debt consisted of the following at December 31, 2022 and 2021:

	As of December 31,
	2022	2021
PNC Facility	$81,250	$65,000
Total	81,250	65,000
Unamortized debt issuance costs	(949)	(1,306)
Total debt	$80,301	$63,694

Credit Facilities

Truist Term Loans and Revolver

In connection with the acquisition of various physician practice assets, the Company entered into Truist Term Loans, all of which have identical underlying terms and provisions. The Term Loans are seven-year loans and require interest only payments for the first two years of the term. For the remaining five years, monthly principal and interest payments are required in amounts sufficient to fully amortize the principal at maturity. The Truist Term Loans may be prepaid in whole or in part at any time without penalty.

On August 31, 2018, the Company entered into a one-year revolving line of credit agreement (“Truist Revolver”) for $10.0 million maturing on August 31, 2019. On April 22, 2019, the Company executed the first amendment to the Truist Revolver which increased the revolving credit limit to $27.0 million and extended the maturity date to April 20, 2020. The Truist Revolver requires monthly interest only payments with the outstanding principal balance due at maturity. The original base interest rate was the one-month LIBOR rate plus an applicable margin of 1.30%.

The Truist Term Loans and Revolver were collateralized by substantially all assets of the Company and guaranteed on a limited basis by the Class A members of the Company and shareholder of AON Partners and Partners of Maryland. In addition, the Company was required to maintain certain financial covenants under these loan agreements relating to debt service coverage and levels of tangible net worth.

On April 20, 2020, the Company modified the arrangement and received an extension of the Truist Revolver from April 20, 2020 to June 4, 2020. On June 4, 2020, the Company received an extension of the Truist Revolver from June 4, 2020 to July 4, 2020. On July 4, 2020, the Company received an extension of the Truist Revolver from July 4, 2020 to September 4, 2020.

On September 4, 2020, the Company modified the arrangement and entered into an Amended and Restated Loan Agreement (“Restated Truist Revolver”), which reduced the bank’s commitment from $27.0 million to $10.0 million, extended the maturity date to September 3, 2021 and increased the interest rate on all amounts outstanding under the Revolver to the greater of LIBOR plus an applicable margin of 3.60% or 4.35%. All other provisions and warranties of the credit agreement remained unchanged. There were no borrowings outstanding at December 31, 2021.

PNC Loan Facility

On April 30, 2021 the Company entered into a Loan Facility with PNC (“PNC Loan Facility”) collateralized by the Company’s assets and outstanding patient accounts receivable. The PNC Loan Facility is guaranteed on a limited basis by the Company and shareholder of AON Partners and Partners of Maryland. $34.6 million of proceeds from the PNC Loan Facility was used to pay off the Truist Term Loans and Truist Revolver. The remaining funds were made available for working capital and acquisition of additional physician practices.

The PNC Loan Facility is interest-only with total principal due at maturity on April 30, 2024. Interest accrues at one-month LIBOR or an alternate base rate plus 1.45%. The maximum balance of the PNC Loan Facility (“Borrowing Base”) is limited to the lesser of the Facility Limit ($65.0 million) or the fair value of the Company’s patient accounts receivable. The Company must maintain a balance of the lesser of the Borrowing Base or 65% of the Facility Limit in the first year and 75% of the Facility Limit in subsequent years (“minimum funding threshold”). The Company can repay the PNC Loan Facility up to the minimum funding threshold at any time without penalty. In accordance with the PNC Loan Facility, the Company pledged $10.0 million of collateral as restricted cash to be released quarterly in increments of $2.5 million. The Company had $5.0 million of restricted cash related to the Loan facility as of December 31, 2021. The restricted cash was fully released as of December 31, 2022.

On April 30, 2021, the Company entered into a $5.0 million revolving line of credit agreement (“PNC Line of Credit”). The PNC Line of Credit has an expiration date of April 30, 2024 and bears interest at a rate per annum equal to the sum of the daily LIBOR rate plus 1.65% or an alternate base rate plus .65% and is due on the first day of each month beginning June 1, 2021. Any outstanding principal and accrued interest will be due on the expiration date. Beginning July 1, 2021, quarterly bank fees equal to 1.65% per day per annum will be due in arrears and will continue on the first day of each quarter thereafter. All debt related to the PNC Line of Credit is collateralized by the Company’s assets. The Company is also subject to 0.20% unused line fee calculated per annum on the unused balance of the PNC Line of Credit.

On July 29, 2021, the Company amended the PNC Loan Facility increasing the Facility Limit to $75.0 million. On February 14, 2022, the Company further amended the PNC Facility and PNC Line of Credit agreements. The primary changes included an increase of the PNC Facility limit from $75.0 million to $125.0 million, an increase of the PNC Line of Credit availability from $5.0 million to $10.0 million, interest charges to be calculated based on the Bloomberg Short-Term Bank Yield Index plus 1.65% and certain financial covenants. As part of the amendment, the Company drew an additional $16.3 million in proceeds under the PNC Loan Facility. On August 15, 2022, the PNC Loan Facility and PNC Line of Credit agreements were amended again to reduce the availability under the PNC Line of Credit from $10.0 million to $1.0 million. As of December 31, 2022 and 2021, no draws had been made on the PNC Line of Credit.

Effective November 23, 2022, the Company entered into Waiver and Amendment No. 6 (“Waiver and Amendment”) under its PNC Facility Loan as the Company was not in compliance with the Delinquency Ratio financial covenant for the period ending October 31, 2022 and the requirement to provide certain annual financial statements. The Waiver and Amendment waives each event of default and also revised future delinquency percentages and financial statement requirements.

The PNC Loan Facility and PNC Line of Credit nonfinancial covenants include restrictions related to unpermitted property liens and the requirement of audited financial statements. Both agreements also contain several financial covenants, including the following ratios: accounts receivable default, delinquency, dilution, days sales outstanding, leverage, and fixed charge coverage. As of December 31, 2022, the Company was in compliance with all financial and nonfinancial debt covenants as required by both loan agreements.

The Company paid approximately $0.3 million and $1.1 million, respectively in debt issuance costs in connection with the Loan Facility in 2022 and 2021 which are being amortized to interest expense on a straight-line basis over the life of the various agreements. The Company recorded a loss on extinguishment of the debt issuance costs on the Truist Term Loans and Revolver in the amount of approximately $0.1 million in 2021.

Interest expense on long-term debt in 2022, 2021, and 2020, including amortization of debt issuance costs, was $3.4 million, $1.4 million, and $1.1 million, respectively.

Basis of Presentation and Significant Accounting Policies (Q3) (Details) $ / shares in Units, $ in Thousands			1 Months Ended		3 Months Ended			9 Months Ended			12 Months Ended
	Sep. 30, 2023 USD ($) shares	Jun. 07, 2023 USD ($)	May 31, 2023 USD ($)	Jan. 31, 2023 USD ($)	Sep. 30, 2023 USD ($) $ / shares shares	Jun. 30, 2023 USD ($)	Sep. 30, 2022 USD ($) $ / shares	Sep. 30, 2023 USD ($) segment $ / shares shares	Sep. 20, 2023 USD ($)	Sep. 30, 2022 USD ($) $ / shares	Dec. 31, 2022 USD ($) Segment $ / shares shares	Dec. 31, 2021 USD ($) $ / shares	Dec. 31, 2020 USD ($) $ / shares
Description Of Business And Significant Accounting Policies [Line Items]
Recapitalization exchange ratio, units \| shares	2,524,000				2,524,000			2,524,000			2,524
Net income (loss) attributable to common shareholders					$ (1,700)			$ (1,700)
Net loss attributable to noncontrolling interest	$ 11,924				11,924		$ 0	11,924		$ 0
Net income (loss) and noncontrolling interest attributable to Legacy AON Shareholders prior to the reverse recapitalization					(15,489)		5,607	$ (27,081)	$ (27,000)	1,227	$ 2,589	$ (105)	$ 21,951
Number of operating segments								1			1
Number of reportable segments								1			1
Revenue					$ 336,305		$ 297,324	$ 955,003		849,272	$ 1,149,670	943,747	724,743
Offering costs											206	0	$ 0
Stock issuance costs								800
Deferred offering costs											300
Proceeds from issuance of redeemable preferred stock								$ 64,996		$ 0
Malpractice insurance, coverage per claim											2,000	2,000
Malpractice insurance, limit per policy period											$ 4,000	$ 4,000
Number of securities called by each warrant (in shares) \| shares	1				1			1
Reverse recapitalization, equity conversion ratio	1				1			1
Earnings (loss) per unit, diluted (in usd per share) \| $ / shares					$ (0.61)		$ 0	$ (0.61)		$ 0	$ 0	$ 0	$ 0
Earnings (loss) per unit, basic (in usd per share) \| $ / shares					$ (0.61)		$ 0	$ (0.61)		$ 0	$ 0	$ 0	$ 0
Accrued dividend rate (in percent)								8.00%
Series C Preferred Stock
Description Of Business And Significant Accounting Policies [Line Items]
Offering costs		$ 500						$ 800
Deferred offering costs		300
Net proceeds from issuance of redeemable convertible stock		64,500
Proceeds from issuance of redeemable preferred stock		$ 65,000
Participating Threshold, 1
Description Of Business And Significant Accounting Policies [Line Items]
Recapitalization exchange ratio, units \| shares	2,524,000				2,524,000			2,524,000			2,524
Participating Threshold, 2
Description Of Business And Significant Accounting Policies [Line Items]
Recapitalization exchange ratio, units \| shares	2,453,000				2,453,000			2,453,000			2,453
Participating Threshold, 3
Description Of Business And Significant Accounting Policies [Line Items]
Recapitalization exchange ratio, units \| shares	1,976,000				1,976,000			1,976,000			1,976
AON LLC
Description Of Business And Significant Accounting Policies [Line Items]
Reverse recapitalization, equity conversion ratio									1
AON LLC \| Series A Preferred Stock
Description Of Business And Significant Accounting Policies [Line Items]
Recapitalization exchange ratio, units \| shares	2,705,000				2,705,000			2,705,000
Preferred Class A
Description Of Business And Significant Accounting Policies [Line Items]
Offering costs								$ 800
Accrued dividend rate (in percent)								8.00%
Series A Preferred Stock
Description Of Business And Significant Accounting Policies [Line Items]
Offering costs								$ 750		$ 0
Series A Preferred Stock \| AON LLC
Description Of Business And Significant Accounting Policies [Line Items]
Recapitalization exchange ratio, units \| shares											2,705
Public Warrant
Description Of Business And Significant Accounting Policies [Line Items]
Fair value of warrants	$ 1,400				$ 1,400			1,400
Private Placement Warrants
Description Of Business And Significant Accounting Policies [Line Items]
Fair value of warrants	$ 1,000				$ 1,000			$ 1,000
Private Placement Warrants \| Measurement Input, Expected Dividend Rate
Description Of Business And Significant Accounting Policies [Line Items]
Warrants, measurement input	0				0			0
Private Placement Warrants \| Measurement Input, Price Volatility
Description Of Business And Significant Accounting Policies [Line Items]
Warrants, measurement input	0.0075				0.0075			0.0075
Private Placement Warrants \| Measurement Input, Risk Free Interest Rate
Description Of Business And Significant Accounting Policies [Line Items]
Warrants, measurement input	0.046				0.046			0.046
Private Placement Warrants \| Measurement Input, Expected Term
Description Of Business And Significant Accounting Policies [Line Items]
Warrants, measurement input	5				5			5
Professional Malpractice Liability Insurance
Description Of Business And Significant Accounting Policies [Line Items]
Malpractice insurance, coverage per claim								$ 1,000			$ 1,000	$ 1,000
Malpractice insurance, limit per policy period								3,000			$ 1,000	$ 1,000
Directors and Officers Liability Insurance
Description Of Business And Significant Accounting Policies [Line Items]
Malpractice insurance, coverage per claim								2,000
Malpractice insurance, limit per policy period								4,000
OCP Management Arizona, LLP
Description Of Business And Significant Accounting Policies [Line Items]
Noncash consideration of equity method investment				$ 2,300
Equity method investment (in percent)				49.00%
Patient Visits
Description Of Business And Significant Accounting Policies [Line Items]
Revenue					$ 238,900		$ 213,800	678,100		606,000
Clinical Trials
Description Of Business And Significant Accounting Policies [Line Items]
Revenue					$ 2,200		$ 1,000	$ 3,700		$ 3,100
MIBA
Description Of Business And Significant Accounting Policies [Line Items]
Payments to acquire interest in subsidiary			$ 200			$ 200
Allocation of income to controlling and noncontrolling interests			56.00%
AON LLC \| Legacy AON Shareholders
Description Of Business And Significant Accounting Policies [Line Items]
Allocation of income to controlling and noncontrolling interests	81.00%							67.90%	100.00%	100.00%
AON LLC \| AON Inc.
Description Of Business And Significant Accounting Policies [Line Items]
Allocation of income to controlling and noncontrolling interests	19.00%

Summary of Significant Accounting Policies and Basis of Presentation (FY)

12 Months Ended

Dec. 31, 2022

Summary of Significant Accounting Policies and Basis of Presentation

3. Summary of Significant Accounting Policies and Basis of Presentation

Basis of Presentation

Accounting Estimates and Assumptions

Segments

Revenue Recognition

The Company monitors revenue and receivables to prepare estimated contractual allowances for the anticipated differences between billed and reimbursed amounts. Payments from third-party payors and Government programs including Medicare and Medicaid may be subject to audit and other retrospective adjustments. Such amounts are considered on an estimated basis when net patient revenue is recorded and are adjusted as final adjustments are determined. For the years ended December 31, 2022, 2021, and 2020, such resulting historic adjustments have been immaterial to the consolidated financial statements.

The Company uses the cost-to-cost measure of progress for the Company’s contract because it best depicts the transfer of control to the customer as the performance obligation is fulfilled. For this method, the Company compares the contract costs incurred to date to the estimated total contract costs through completion. As part of the client proposal and contract negotiation process, the Company develops a detailed project budget for the direct costs and reimbursable costs based on the scope of the work, the complexity of the study, the geographical location involved and the Company’s historical experience. The estimated total contract costs at the project level are reviewed and revised periodically throughout the life of the contract, with adjustments to revenue resulting from such revisions being recorded on a cumulative basis in the period in which the revisions are identified. Contract costs consist primarily of direct labor and other reimbursable project-related costs such as travel, third-party vendor costs and investigator fees. The Company establishes pricing based on the Company’s internal pricing guidelines, discount agreements, if any, and negotiations with the client. The transaction price is the contractually defined amount. For the year ended December 31, 2022, the Company recognized revenue of $4.3 million related to the clinical trial which is included within other revenue.

Short-term Marketable Securities

Cost of Revenue

Business Combinations

Cash and Cash Equivalents

Restricted Cash

	As of December 31,
	2022	2021
Cash and cash equivalents	$26,926	$27,354
Restricted cash	—	5,000
Total cash, cash equivalents and restricted cash shown in the statements of cash flow	$26,926	$32,354

Accounts Receivable

	As of December 31,
	2022	2021
Medicare	25%	27%
Managed Medicare	25%	21%
Other Commercial	17%	17%
BCBS	17%	16%
Managed Medicaid	8%	12%
Other	8%	7%
	100%	100%

As of December 31, 2022, December 31, 2021, and January 1, 2021, the accounts receivable, net balances were $136.1 million, $111.2 million, and $80.4 million, respectively.

Inventories

Other Receivables

Property and Equipment

Leasehold improvements			1 – 15 years
Furniture, fixtures and equipment			7 years
Medical equipment			5 – 10 years
Computer equipment			5 years
Signs			7 years
Automobiles			5 years
Software			7 years

Goodwill

Leases

Income Taxes

Concentration of Credit Risk

Equity-Based Compensation

Debt Issuance Costs

Offering Costs

The Company defers specific incremental costs directly attributable to proposed offerings of securities. These costs consist of legal, accounting, and other similar expenses incurred through the balance sheet date that are directly related to a potential offering. If the offering is completed, these costs will be charged against the gross proceeds of the offering. These offering costs will be allocated to the separable financial instruments issued in the transaction on a relative fair value basis of the securities issued, compared to total proceeds received. Offering costs associated with any instruments classified as liabilities will be expensed as incurred, presented as non-operating expenses in the Consolidated Statement of Operations and Comprehensive Income (Loss). At December 31, 2022, the Company had incurred approximately $0.3 million of offering costs which are included in other assets in the accompanying Consolidated Balance Sheets.

Professional Liability

The Company maintains insurance policies for exposure to professional malpractice insurance risk. The limits of malpractice insurance provide each physician/advanced practice provider with a dedicated $1.0 million limit per claim and a $3.0 million limit in the aggregate per policy period — on a first dollar basis, as no deductible applies. The policy further then extends coverage to the Company, by providing a $2.0 million limit per claim and a $4.0 million limit in the aggregate per policy period — on a first dollar basis, additionally, as no deductible applies. Reserves are established for estimates of the loss that will ultimately be incurred on claims that have been reported but not paid and claims that have been incurred but not reported. These reserves are established based on consultation with a third-party actuary. The actuarial valuations consider a number of factors, including historical claims payment patterns, changes in case reserves and the assumed rate of increase in healthcare costs. Management believes the use of actuarial methods to account for these reserves provides a consistent and effective way to measure these subjective accruals. However, due to the sensitive nature of this estimation technique, recorded reserves could differ from ultimate costs related to these claims due to changes in claims reporting, claims payment and] settlement practices and differences in assumed future cost increases. Accrued unpaid claims and expenses that are expected to be paid within the next twelve months are classified as current liabilities and included in accrued other. All other accrued unpaid claims and expenses are classified as long-term liabilities and included in other long-term liabilities. Insurance recoveries associated with the unpaid claims are classified as long-term assets included in other assets.

Fair Value of Financial Instruments

Level 1

Inputs to the valuation methodology are quoted prices (unadjusted) for an identical asset or liability in an active market.

Level 2

Level 3

Inputs to the valuation methodology are unobservable and significant to the fair value measurement of the asset or liability.

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

Commitments and Contingencies (FY)	12 Months Ended
Commitments and Contingencies (FY)	Dec. 31, 2022
Commitments and Contingencies [Abstract]
Commitments and Contingencies	16. Commitments and Contingencies Florida Cancer Specialists Service In October 2017, the Company entered into a Services Agreement (“Agreement’) with Florida Cancer Specialists, P.L. (“FCS”). FCS provides certain medical services and practice management and administration services to the various physician practices. These services include but are not limited to insurance billing, collections, accounts payable, purchasing, payroll processing, and compliance and coding support. The initial agreement has a five-year term which renews annually unless either party terminates with twelve months written notice. Fees for services are based on a percentage of full-time equivalent (“FTE”) revenue, as defined, subject to a maximum percentage per FTE at defined revenue levels. For the years ended December 31, 2021 and 2020, AON Partners and Partners of Maryland collectively incurred costs of approximately $4.7 million and $18.7 million, respectively, related to this Agreement which are included in general and administrative expenses in the Consolidated Statements of Operations and Comprehensive Income (Loss). As additional security for payments under the Agreement, AON LLC deposited $1.0 million with FCS. During 2021, the agreement was terminated, and the Company settled with FCS. Contingencies The Company, through its arrangements with certain contracts, is subject to the Medicare and Medicaid fraud and abuse laws which prohibit, among other things, any false claims, or any bribe, kick- back or rebate in return for the referral of Medicare and Medicaid patients. Violation of these prohibitions may result in civil and criminal penalties and exclusion from participation in the Medicare and Medicaid programs. Management has implemented policies and procedures they believe will assure that the Company is in substantial compliance with these laws. From time to time, the Company may receive requests for information from government agencies pursuant to their regulatory or investigational authority. Such requests can include subpoenas or demand letters for documents to assist the government in audits or investigations. Management believes that the outcome of any of these investigations would not have a material adverse effect on the Company. Laws and regulations governing the Medicare program are complex and subject to interpretation. The Company believes that it is complying in all material respects with all applicable laws and regulations and is not aware of any pending or threatened investigations involving allegations of potential wrongdoing that would have a material effect on the Company’s consolidated financial statements. Compliance with such laws and regulations can be subject to future government review and interpretation, as well as significant regulatory action including fines, penalties, and exclusion from the Medicare Program. The Company and its affiliates are subject to various legal proceedings and claims arising in the normal course of their business. In the opinion of management, the amount of the ultimate liability, if any, with respect to these lawsuits and claims will not have a material effect on the consolidated financial statements of the Company.

Redeemable Noncontrolling Interest - Schedule of Ownership (Q3) (Details) - AON LLC	Sep. 30, 2023 shares
Equity, Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance (in units)	0
Common Units issued (in units)	34,724,025
Series A Preferred Units Issued	6,651,610
Total Units Issued	41,375,635
Ending balance (in units)	41,375,635
Allocation of income to controlling and noncontrolling interests (in percent)	1
Allocation of losses to controlling and noncontrolling interests (in percent)	1
AON Inc.
Equity, Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance (in units)	0
Common Units issued (in units)	6,614,229
Series A Preferred Units Issued	6,651,610
Total Units Issued	13,265,839
Ending balance (in units)	13,265,839
Allocation of income to controlling and noncontrolling interests (in percent)	0.321
Allocation of losses to controlling and noncontrolling interests (in percent)	0.19
Common unit excluded from issuance (in units)	2,839,375
Legacy AON Shareholders
Equity, Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance (in units)	0
Common Units issued (in units)	28,109,796
Series A Preferred Units Issued	0
Total Units Issued	28,109,796
Ending balance (in units)	28,109,796
Allocation of income to controlling and noncontrolling interests (in percent)	0.679
Allocation of losses to controlling and noncontrolling interests (in percent)	0.81

Stockholders' Equity (FY)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Stockholders' Equity [Abstract]

Stockholders' Equity

12. Equity

Prior Period Presentation

Class A Units

AON LLC had authorized 19,495,376 units of Class A Units, of which 19,495,376 units were issued and were outstanding as of December 31, 2022.

Class A-1 Units

AON LLC had authorized 3,000,245 units of Class A-1 Units, of which 1,842,520 units were issued and were outstanding as of December 31, 2022.

Class B Units (Profit Interest)

The following table summarizes the changes to AON LLC’s Class A, Class A-1, and Class B Units for the three and nine months ended September 30, 2023, and 2022.

in thousands, except for share and per share amounts	Three Months Ended September 30,		Nine Months Ended September 30,
	2023	2022	2023	2022
Class A Units, value
Beginning of Period	$7,725	$7,725	$7,725	$7,725
Issuance of Units	—	—	—	—
Impact of the Reverse Recapitalization	(7,725)	—	(7,725)	—
End of Period	$—	$7,725	$—	$7,725
Class A Units, units
Beginning of Period	19,495,376	19,495,376	19,495,376	19,495,376
Issuance of Units	—	—	—	—
Impact of the Reverse Recapitalization	(19,495,376)	—	(19,495,376)	—
End of Period	—	19,495,376	—	19,495,376

in thousands, except for share and per share amounts	Three Months Ended September 30,		Nine Months Ended September 30,
	2023	2022	2023	2022
Class A-1 Units, value
Beginning of Period	$31,040	$28,500	$28,500	$28,500
Issuance of Units	7,185	—	9,725	—
Impact of the Reverse Recapitalization	(38,225)	—	(38,225)	—
End of Period	$—	$28,500	$—	$28,500
Class A-1 Units, units
Beginning of Period	2,281,696	1,842,520	1,842,520	1,842,520
Issuance of Units	718,549		1,157,725
Impact of the Reverse Recapitalization	(3,000,245)		(3,000,245)
End of Period	—	1,842,520	—	1,842,520

in thousands, except for share and per share amounts	Three Months Ended September 30,		Nine Months Ended September 30,
	2023	2022	2023	2022
Class B Units, value
Beginning of Period	$80	$90	$80	$80
Equity based compensation	10	5	10	15
Impact of the Reverse Recapitalization	(90)	—	(90)
End of Period	$—	$95	$—	$95
Class B Units, units
Beginning of Period	4,703,628	4,703,628	4,703,628	4,703,628
Units Vested	910,548	—	910,548	—
Impact of the Reverse Recapitalization	(5,614,176)	—	(5,614,176)	—
End of Period	—	4,703,628	—	4,703,628

Class B-1 Units

Mezzanine Equity Class C Units

Class C Unit Redemption Right

Class C Unit Option to Purchase Additional Units

Series A Preferred Stock (Mezzanine Equity)

The Series A Preferred Stock are not being accreted to redemption value, as the Series A Preferred Stock are not redeemable, nor are they probable of becoming redeemable.

Dividends

Voting

Conversion Rights

Liquidation Preferences

(i)	The Original Issue Price of $10 per Series A Preferred Stock multiplied by the Applicable Percentage plus any Accrued Dividends on such share of Series A Preferred Stock; or

(ii)	Such amount per share as would have been payable had all shares of Series A Preferred Stock been converted into Common Stock immediately prior to such Deemed Liquidation Event.

Distributions to Class A and Class A-1 Members

Class A-1 Anti-Dilution Feature

12. Stockholders’ Equity

Class A units

Class A-1 units

Class B units

The entire disclosure for equity.

Stockholders' Equity (FY) (Details) $ in Thousands		1 Months Ended	12 Months Ended
Stockholders' Equity (FY) (Details) $ in Thousands	Oct. 31, 2017 Vote	Mar. 31, 2020 USD ($) Vote shares	Dec. 31, 2022 USD ($) Vote shares	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($)
Stockholders' Equity [Abstract]
Capital contribution \| $			$ 0	$ 0	$ 28,500
Number of new issued shares value \| $					28,500
Class A Units [Member]
Stockholders' Equity [Abstract]
Number of votes per unit \| Vote			1
Minimum percentage interest			70.00%
Units outstanding (in shares)			19,495,376	19,495,376
Capital contribution \| $			$ 7,700	$ 7,700
Percentage of preferred return on capital contributions		8.00%
Number of new units assigned based on their percentage interest relative to the Class A Members (in shares)		101
Class A-1 Units [Member]
Stockholders' Equity [Abstract]
Number of votes per unit \| Vote		1
Units outstanding (in shares)			1,842,520	1,842,520
Capital contribution \| $		$ 30,000
Common units issued (in shares)		1,842,520
Percentage of preferred return on capital contributions		4.00%
Brokerage fee \| $		$ 1,500
Number of new issued shares value \| $		$ 28,500
Class B Units [Member]
Stockholders' Equity [Abstract]
Number of votes per unit \| Vote	0
Units outstanding (in shares)			4,703,628	4,703,628
Common units issued (in shares)			5,614,176	5,614,176
Cliff vesting period			5 years
Percentage of collar removed		30.00%
Equity-based compensation expense \| $				$ 20	$ 20
Common units, vested (in shares)			4,703,628	4,703,628
Units issued (in units)			0
Units Vested (in units)			0
Units forfeited (in units)			0
Class B Units [Member] \| Maximum [Member]
Stockholders' Equity [Abstract]
Awards vesting period			5 years
Class B Units [Member] \| Minimum [Member]
Stockholders' Equity [Abstract]
Awards vesting period			2 years

Summary of Significant Accounting Policies and Basis of Presentation, Revenue Recognition (FY) (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Apr. 30, 2020	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue Recognition [Abstract]
Revenue		$ 336,305	$ 297,324	$ 955,003	$ 849,272	$ 1,149,670	$ 943,747	$ 724,743
Revenue recognized							3,700	13,500
Cash received from government stimulus programs	$ 24,000
Advances from government grants	$ 17,200
Outstanding liability						0	3,742
Services for Patient Visits [Member]
Revenue Recognition [Abstract]
Revenue						818,500	683,000	542,000
Other Revenue [Member]
Revenue Recognition [Abstract]
Revenue						11,738	5,505	3,224
Revenue recognized						4,300
HHS Grant Income [Member]
Revenue Recognition [Abstract]
Revenue						0	$ 0	6,841
Revenue recognized						$ 6,800		$ 24,000

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Earnings (Loss) Per Share [Abstract]

Earnings (Loss) Per Share (FY)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Earnings (Loss) Per Share

13. Net Loss Per Share

Net loss attributable to Class A Common Stockholders for basic and diluted loss per share			$ (1,791,768)
Series A Deemed Dividend			(2,089,000)
Series A Preferred Cumulative Dividends			(133,032)
Undistributed Net Loss attributable to Class A Common Stockholders			$ (4,013,000)

Weighted-average shares for basic and diluted loss per share			6,614,229
Basic & Diluted loss per share of Class A Common Stock			$ (0.61)

Series A Preferred Stock			6,651,610
Class B Common Stock			25,109,551
Class B Prefunded Warrants			3,000,245
Public and Private Warrants			14,450,883

18. Earnings (Loss) Per Share

Earnings (Loss) Per Share (FY) (Details) - $ / shares	3 Months Ended		9 Months Ended		12 Months Ended
Earnings (Loss) Per Share (FY) (Details) - $ / shares	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Earnings (Loss) Per Share [Abstract]
Earnings (loss) per unit, basic (in usd per share)	$ (0.61)	$ 0	$ (0.61)	$ 0	$ 0	$ 0	$ 0
Earnings (loss) per unit, diluted (in usd per share)	$ (0.61)	$ 0	$ (0.61)	$ 0	$ 0	$ 0	$ 0

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Operating right of use assets, net

CONSOLIDATED BALANCE SHEETS (FY) (Parenthetical) - USD ($)
$ in Thousands

Sep. 30, 2023

Dec. 31, 2022

Dec. 31, 2021

Assets

$ 46,138

^[1]

$ 43,724

^[1],[2]

$ 0

^[2]

Liabilities

Current portion operating lease liability

120,383

^[3]

106,495

^[3],[4]

92,908

^[4]

7,123

^[5]

9,177

^[5],[6]

^[6]

42,261

^[7]

$ 37,224

^[7],[8]

$ 0

^[8]

Class A Units [Member]

19,495,376

Class A-1 Units [Member]

1,842,520

Class B Units [Member]

4,703,628

Operating right of use assets, net

Assets

11,476

$ 13,077

Liabilities

Current portion operating lease liability

112,740

102,113

$ 88,799

1,912

1,836

$ 9,994

$ 11,631

[1]	Includes related party operating right-of-use assets, net of $11,476 and $13,077 at September 30, 2023 and December 31, 2022, respectively
[2]	Includes related party operating lease right-of-use assets, net of $13,077 at December 31, 2022
[3]	Includes amounts due to related party of $112,740 and $102,113 at September 30, 2023 and December 31, 2022, respectively
[4]	Includes amounts due to related party of $102,113 and $88,799 at December 31, 2022 and 2021, respectively
[5]	Includes related party current portion of operating lease liabilities of $1,912 and $1,836 at September 30, 2023 and December 31, 2022, respectively
[6]	Includes related party current portion of operating lease liabilities of $1,836 at December 31, 2022
[7]	Includes related party long-term operating lease liabilities of $9,994 and $11,631 at September 30, 2023 and December 31, 2022, respectively
[8]	Includes related party long-term operating lease liabilities of $11,631 at December 31, 2022

Accrued Other (FY)

12 Months Ended

Dec. 31, 2022

Accrued Other [Abstract]

Accrued Other

10. Accrued Other

Accrued other consisted of the following at December 31, 2022 and 2021:

	As of December 31,
	2022	2021
Refund liability	$14,544	$8,306
Deferred social security taxes – COVID	378	378
Current portion of finance lease liability	425	—
Other	2,453	5,108
Total accrued other	$17,800	$13,792

Variable Interest Entities (Q3) (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Schedule of Variable Interest Entities

The assets of AON Partners, Partners of Maryland, AON Central Services, and MIBA as of September 30, 2023 and December 31, 2022, are as follows:

	As of September 30, 2023	As of December 31, 2022
Assets
Cash and cash equivalents	$33,083	$26,844
Accounts receivable	141,039	136,098
Inventories	37,844	36,476
Prepaid expenses and other current assets	869	846
Goodwill and intangibles, net	180	180
Other receivables	36,294	28,139
Other assets	2,014	1,489
Total assets	$251,323	$230,072

The liabilities of AON Partners, Partners of Maryland, AON Central Services, and MIBA as of September 30, 2023 and December 31, 2022, are as follows:

	As of September 30, 2023	As of December 31, 2022
Liabilities
Accounts payable	$114,779	$102,783
Accrued compensation and benefits	22,747	6,021
Accrued other	16,038	15,926
Other long-term liabilities	137	452
Due to AON LLC and subsidiaries, net	134,344	128,204
Total liabilities	$288,045	$253,386

The assets of AON Partners and Partners of Maryland as of December 31, 2022 and 2021, are as follows:

	As of December 31,
Assets	2022	2021
Cash and cash equivalents	$26,844	$24,074
Accounts receivable	136,098	111,183
Inventories	36,476	34,529
Property and equipment, net	—	108
Prepaid expenses and other current assets	846	374
Goodwill and intangibles, net	180	180
Other receivables	28,139	24,950
Other assets	1,489	1,241
Total assets	$230,072	$196,639

The liabilities of AON Partners and Partners of Maryland as of December 31, 2022 and 2021, are as follows:

	As of December 31,
Liabilities	2022	2021
Accounts payable	$102,783	$89,275
Accrued compensation and benefits	6,021	6,504
Accrued other	15,926	9,346
Medicare advance payment	—	3,742
Other long-term liabilities	452	81
Due to AON and subsidiaries, net	128,204	102,090
Total liabilities	$253,386	$211,038

Leases - Lease Costs (Q3) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Leases [Abstract]
Operating lease costs	$ 2,820	$ 3,161	$ 8,361	$ 9,297	$ 12,465
Amortization of finance lease right-of-use assets	122	185	354	413	523
Interest on finance lease liabilities (included in interest expense)	35	19	79	60	79
Variable lease costs	560	862	1,742	2,232	2,737
Total lease costs	$ 3,537	$ 4,227	$ 10,536	$ 12,002	$ 15,804

Business (Q3)

9 Months Ended

Sep. 30, 2023

Business

1. Business

American Oncology Network, Inc. (“AON”, “New AON”, “AON Inc.”, or the “Company”), through its subsidiary companies and variable interest entities (together, “its subsidiaries”), is an alliance of physicians and seasoned healthcare leaders who provide comprehensive oncology services across 33 oncology practices located in nineteen states (Arizona, Arkansas, Florida, Georgia, Iowa, Idaho, Indiana, Louisiana, Maryland, Missouri, Michigan, North Carolina, Nevada, Nebraska, Ohio, South Carolina, Texas, Virginia and Washington). The Company also provides expertise in drug procurement and payor contracting, along with practice diversification through centralized laboratory and pathology services, as well as specialty pharmacy services, clinical research, radiation oncology, and imaging. During the nine months ended September 30, 2023 and 2022, the Company entered into affiliation agreements with or acquired the following oncology practices.

Nine Months Ended September 30, 2022			Nine Months Ended September 30, 2023
State			State
Arizona			Texas^(a)
Georgia^(a)			Florida^(a)
Louisiana^(a)			Arkansas^(a)
Georgia^(a)
Georgia^(a)
Georgia^(a)

(a)	The Company entered into affiliation agreements with the physicians for these respective practices. The Company evaluated each of the affiliation agreements and determined that the transactions did not represent a business combination.

The operations of the practices that were acquired have been included in the Company’s condensed consolidated financial statements since the date of acquisition. The Company intends to continue to pursue additional purchases of physician practices in addition to seeking out new affiliation relationships.

Business Combination Agreements

Digital Transformation Opportunities Corp. (“DTOC”), American Oncology Network, LLC (“AON LLC”), GEF AON Holdings Corp. (“AON Class C Preferred Investor”), and DTOC Merger Sub, Inc., a direct, wholly owned subsidiary of DTOC (“Merger Sub”) entered into a Business Combination Agreement (the “Business Combination Agreement”), dated as of June 14, 2023 (which further amended and restated the Business Combination Agreement entered into by DTOC and AON as of October 5, 2022, and amended and restated on January 6, 2023, and April 27, 2023), pursuant to which, among other transactions, on September 20, 2023 (the “Closing Date”), DTOC and AON undertook a series of transactions (the “Business Combination”) resulting in the organization of the combined post-business combination company as an umbrella partnership C corporation, in which substantially all of the assets and the business of the combined company are held by AON LLC, and DTOC became a member of AON LLC. In connection with the closing of the Business Combination (“the Closing”), DTOC changed its name to “American Oncology Network, Inc.”. The Business Combination was completed on September 20, 2023.

As a result of, and in connection with, the Closing, among other things, (i) AON LLC amended and restated its operating agreement (the “Amended and Restated AON LLC Agreement”) to reclassify its existing Class A units, Class A-1 units and Class B units into a single class of AON LLC common units (“AON LLC Common Units”) that can be exchanged on a one-to-one basis for shares of New AON Class A common stock (“New AON Class A Common Stock”) and its existing AON LLC Class C units into AON LLC Series A preferred units (AON LLC Series A Preferred Units”); (ii) AON LLC converted profit pool units of certain of AON LLC’s subsidiaries into an equal number of AON LLC Common Units and shares of New AON Class B common stock (“New AON Class B Common Stock”), which together are exchangeable into shares of New AON Class A Common Stock (together with the New AON Class B Common Stock, the “New AON Common Stock”); (iii) New AON amended and restated its charter (the “Charter”) to provide for (a) the conversion of all existing shares of DTOC Class B common stock into

shares of New AON Class A Common Stock on a one-to-one basis, (b) amendment of the terms of New AON Class B Common Stock to provide holders voting rights but no economic rights and (c) designation of a new series of New AON preferred stock as Series A convertible preferred stock (the “New AON Series A Preferred Stock” or “Series A Preferred Stock”) with such rights and preferences as provided for in the certificate of designation of the New Aon Series A Preferred Stock (the “New AON Series A Certificate of Designation”); and (iv) among other things, (a) AON LLC issued common units to New AON in exchange for a combination of cash and shares of New AON Class B Common Stock and warrants to acquire shares of New AON Class B Common Stock (the “Class B Prefunded Warrants”), (b) New AON was admitted as a member of AON LLC, (c) AON LLC distributed shares of New AON Class B common stock or Class B Prefunded Warrants, as applicable, to AON LLC equity holders, (d) New AON reserved a specified number of additional shares of New AON Class A Common Stock after the Closing for issuance to eligible participants, (e) Merger Sub merged with and into the AON Class C Preferred Investor whereby the separate existence of Merger Sub ceased and New AON issued a number of shares of New AON Series A Preferred Stock equal to the number of AON LLC Series A preferred units held by the AON Class C Preferred Investor to AEA Growth Management LP, the parent of AON Class C Preferred Investor (“AEA Growth”) in exchange for all the shares of common stock held by AEA Growth in the AON Class C Preferred Investor (the “First Step”), (f) promptly after the First Step, the AON Class C Preferred Investor merged with and into New AON whereby the separate existence of the AON Class C Preferred Investor ceased and New AON held all the AON LLC Series A preferred units and (g) from and after the Closing (but subject to lock-up restrictions), the AON LLC common equity holders (other than New AON), referred to herein as “Legacy AON Shareholders” (former AON LLC Class A, Class A-1, and Class B unit holders), will have the right (but not the obligation) to exchange AON LLC Common Units together with an equal number of shares of New AON Class B Common Stock (whether held directly or indirectly through Class B Prefunded Warrants) for shares of New AON Class A Common Stock.

Upon the consummation of the Business Combination, the outstanding membership units in AON LLC and the outstanding shares in AON Inc. (New AON) are as follows:

•	AON LLC Common Units held by the Legacy AON Shareholders - 28,109,796

•	AON LLC Common Units held by New AON - 9,532,354

•	AON LLC Series A Preferred Units held by New AON - 6,651,610

•	Class A Common Stock held by the former AON LLC Class B-1 unit holders - 1,047,343

•	Class A Common Stock held by the DTOC unredeemed shareholders - 147,511

•	Class A Common Stock held by the DTOC Sponsor and their permitted transferees - 5,419,375^(a)

•	Class B Common Stock held by Legacy AON Shareholders - 25,109,551^(b)

•	New AON Series A Preferred Stock held by AEA Growth Management LP - 6,651,610

(a)	Sponsor Earnout Shares of 2,839,375 are subject to vesting and forfeiture provisions and are not outstanding for GAAP purposes as of the Closing Date.

(b)	Certain Legacy AON Shareholders hold 3,000,245 Class B Prefunded Warrants, which underlying shares of Class B common stock are not outstanding as of the Closing Date.

Accounting Treatment for the Business Combination

As AON LLC does not meet any of the characteristics of a VIE under ASC 810, the Business Combination was evaluated under ASC 805, Business Combinations. Notwithstanding the legal form of the Business Combination pursuant to the Business Combination Agreement, the Business Combination was accounted for as a reverse

recapitalization in accordance with GAAP. Under this method of accounting, DTOC was treated as the acquired company and AON LLC was considered the acquirer for financial statement reporting purposes. AON LLC was determined to be the accounting acquirer based on, in summary, an evaluation of the following primary facts and circumstances:

•	AON LLC’s directors will represent a majority of the board seats for New AON’s board of directors;

•	AON LLC’s senior management will be the senior management of the combined company;

•	AON LLC’s operations comprising the ongoing operations of the post-combination company; and

•	AON LLC’s relative size (i.e., assets, revenues, and earnings) is significantly larger compared to DTOC.

Accordingly, for accounting purposes, the financial statements of the post-combination entity will represent a continuation of the financial statements of AON LLC with the acquisition being treated as the equivalent of AON LLC issuing stock for the net assets of DTOC, accompanied by a recapitalization. The net assets of DTOC are stated at historical cost, with no goodwill or other intangible assets recorded. Refer to Note 3 for additional information.

Accounting for the Earnout Shares

Following the Closing and for five years thereafter, the DTOC Sponsor agreed to subject 35%, or 2,839,375 shares of New AON Class A common stock held by it as of the Closing (the “Sponsor Earnout Shares”) to the following vesting and forfeiture provisions:

•	the Sponsor Earnout Shares will vest when the volume-weighted average price of the New AON Class A common stock equals or exceeds $13.50 per share for any 20 trading days within any 30 trading day period beginning after the Closing and ending 60 months following the Closing;

•	the Sponsor Earnout Shares will be released immediately upon the consummation of a change of control transaction within the 60-month period following the Closing; and

•	if the Sponsor Earnout Shares are not released pursuant to the foregoing provisions on or before the date that is 60 months after the Closing, then the Sponsor Earnout Shares will be forfeited immediately following such date.

As the Business Combination was accounted for as a reverse recapitalization, the issuance of the Sponsor Earnout Shares to the Company’s existing shareholders will be accounted for as an equity transaction. The accounting for the Sponsor Earnout Shares was evaluated under ASC Topic 480, Distinguishing Liabilities from Equity, and ASC Subtopic 815-40, Derivatives and Hedging — Contracts in Entity’s Own Equity, to determine if the Sponsor Earnout Shares should be classified as a liability or within equity. As part of that analysis, it was determined that the Sponsor Earnout Shares are freestanding, do not meet the criteria within ASC 480 to be classified as a liability, and meet the criteria in ASC 815-40 to be considered indexed to the post-combination entity’s common stock and classified within equity.

Warrants

As of the Closing Date, New AON assumed the outstanding warrants (Public Warrants and Private Placement Warrants) that were issued by DTOC as part of DTOC’s IPO. Further, New AON issued the Class B Prefunded Warrants to former Class A-1 unit holders, in lieu of New AON Class B Common Stock. The accounting treatment for the Public Warrants, the Private Placement Warrants, and the Class B Prefunded Warrants, collectively referred to as “the Warrants”, is disclosed in Note 2.

Public Warrants

As of the Closing Date, New AON assumed 8,337,500 public warrants (the “Public Warrants”) issued by DTOC in its IPO. Each whole warrant entitles the holder to purchase one share of New AON Class A Common Stock at a price of $11.50 per share, subject to adjustment. The warrants will become exercisable on the later of 12 months from the closing of the DTOC Initial Public Offering or 30 days after the completion of its initial business combination and will expire five years after the Closing of the Business Combination, or earlier upon redemption or liquidation.

Private Warrants

As of the Closing Date, New AON assumed 6,113,333 Private Placement Warrants held by the DTOC Sponsor (the “Private Placement Warrants” or “Private Warrants”). The Private Placement Warrants will be non-redeemable

in certain circumstances so long as they are held by the Sponsor or its permitted transferees. The Private Placement Warrants may also be exercised by the Sponsor and its permitted transferees for cash or on a cashless basis. Otherwise, the Private Placement Warrants have terms and provisions that are identical to those of the Public Warrants, including as to exercise price, exercisability, and exercise period.

Class B Prefunded Warrants

As of the Closing Date, New AON issued 3,000,245 of Class B Prefunded Warrants to former AON Class A-1 unitholders. Because the Class B Warrants are prefunded, there was not any cash consideration exchanged as part of the Class B Warrant issuance. Each Class B Prefunded Warrant entitles the holder to purchase one share of New AON Class B common stock at a price of $0.01 per share. The exercise term of the Class B Warrant shall continue indefinitely so long as the holder of the Class B Warrant is also the holder of an AON LLC Common Unit, provided that the number of shares of Common Stock that this Warrant is exercisable for shall not exceed the number of AON LLC Common Units held by holder.

Transaction Expenses

In connection with the Reverse Recapitalization, AON LLC incurred costs of $24.6 million and $30.6 million during the three and nine months ended September 30, 2023, respectively. Of the total costs incurred during the three months ended September 30, 2023, $24.6 million were reported as transaction expenses in the condensed consolidated statements of operations and comprehensive loss. Of the total costs incurred during the nine months ended September 30, 2023, $29.8 million were reported as transaction expenses in the condensed consolidated statements of operations and comprehensive loss and $0.8 million were reported as a reduction of Series A Preferred Stock presented as mezzanine equity on the condensed consolidated balance sheet at September 30, 2023. At December 31, 2022, the Company had accrued $0.3 million of transaction costs related to the Reverse Recapitalization, which were reported as other assets on the condensed consolidated balance sheet. AON LLC recorded $0.2 million of transaction expenses in connection with the Reverse Recapitalization during the three and nine months September 30, 2022, which were reported as transaction expenses in the condensed consolidated statements of operations and comprehensive loss.

Fair Value Measurements (FY)

12 Months Ended

Dec. 31, 2022

Fair Value Measurements [Abstract]

Fair Value Measurements

6. Fair Value Measurements

The following table summarizes the Company’s financial assets that are measured at fair value on a recurring basis:

	As of December 31, 2022
	Amortized Cost	Gross Unrealized Gains	Gross Unrealized Losses	Estimated Fair Value
Cash equivalents⁽¹⁾
Level 1:
Money market funds	$109	$—	$—	$109
Marketable securities
Level 2:
Corporate bonds	7,742	6	(125)	7,623
U.S. Treasury securities	2,226	6	(4)	2,228
Level 2 total	9,968	12	(129)	9,851
Total	$10,077	$12	$(129)	$9,960

(1)	Included in cash and cash equivalents in the Consolidated Balance Sheet at December 31, 2022

The Company uses quoted prices in active markets for identical assets to determine the fair value of its Level 1 investments. The fair value of Level 2 investments is determined using pricing based on quoted market prices or alternative market observable inputs.

The fair value of the Company’s marketable securities as of December 31, 2022, by remaining contractual maturities, were as follows:

	As of December 31, 2022
	Corporate Bonds	U.S. Treasury Securities	Total
Due within one year	$3,660	$1,073	$4,733
Due within one to five years	3,963	1,155	5,118
Total	$7,623	$2,228	$9,851

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

Reverse Recapitalization (FY) (Details)	Sep. 20, 2023 shares	Sep. 30, 2023 shares	Dec. 31, 2022 person shares
Business Combination Agreement [Abstract]
Reverse recapitalization, equity conversion ratio		1
Reverse Recapitalization [Abstract]
Recapitalization exchange ratio, units		2,524,000	2,524
Common Class A
Business Combination Agreement [Abstract]
Shares issued (in shares)	1,047,343
Participating Threshold, 1
Reverse Recapitalization [Abstract]
Recapitalization exchange ratio, units		2,524,000	2,524
Participating Threshold, 2
Reverse Recapitalization [Abstract]
Recapitalization exchange ratio, units		2,453,000	2,453
Participating Threshold, 3
Reverse Recapitalization [Abstract]
Recapitalization exchange ratio, units		1,976,000	1,976
Subsequent Event [Member] \| Common Class A
Business Combination Agreement [Abstract]
Shares issued (in shares)	1,047,343
AON LLC
Business Combination Agreement [Abstract]
Reverse recapitalization, equity conversion ratio	1
Reverse Recapitalization [Abstract]
Number of board of managers designated by company \| person			3
Number of board of managers designated by majority common unit holders \| person			2
AON LLC \| Series A Preferred Stock
Reverse Recapitalization [Abstract]
Recapitalization exchange ratio, units			2,705
AON LLC \| Subsequent Event [Member]
Business Combination Agreement [Abstract]
Reverse recapitalization, equity conversion ratio	1
Digital Transformation Opportunities Corp. ("DTOC") \| Common Class B
Business Combination Agreement [Abstract]
Reverse recapitalization, equity conversion ratio	1
Digital Transformation Opportunities Corp. ("DTOC") \| Subsequent Event [Member] \| Common Class B
Business Combination Agreement [Abstract]
Reverse recapitalization, equity conversion ratio	1

Income Taxes (Q3)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Income Taxes [Abstract]

Income Taxes

9. Income Taxes

13. Income Taxes

The income tax expense (benefit) in 2022, 2021, and 2020 consisted of the following:

	Year Ended December 31,
	2022	2021	2020
Current
Federal	$—	$(306)	$152
State	—	(20)	123
	—	(326)	275
Deferred
Federal	—	433	(922)
State	—	353	(136)
	—	786	(1,058)
Total income tax expense (benefit)	$—	$460	$(783)

The differences between the federal tax rate and the Company’s effective tax rate for the years ended December 31, 2022, 2021, and 2020 are as follows:

	Year Ended December 31,
	2022	2021	2020
Federal statutory income tax rate	21.00%	21.00%	21.00%
State taxes, net of federal benefit	(11.94)	(97.95)	(0.80)
State rate change	(2.15)	(3.41)	0.07
Other	(3.71)	3.00	0.07
Nontaxable passthrough LLC income	(87.14)	(658.26)	(27.31)
Increase in valuation allowance	83.94	864.95	3.26
Effective tax rate	—%	129.33%	(3.71)%

Components of the net deferred tax assets and liabilities at December 31, 2022 and 2021 are as follows:

	As of December 31,
	2022	2021
Deferred tax assets
Net operating loss carryforwards	$6,589	$5,166
Accrued expenses	165	426
Deferred tax assets	6,754	5,592
Valuation allowance	(5,835)	(3,662)
Net deferred tax asset	919	1,930
Deferred tax liabilities
Prepaid expenses	—	64
Accounting method change	918	1,866
Fixed assets	1	—
Deferred tax liabilities	919	1,930
Net deferred tax asset	$—	$—

Long-term Debt (FY)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Long-term Debt

8. Long-term Debt

Debt consisted of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
PNC Facility	$81,250	$81,250
Total	81,250	81,250
Unamortized debt issuance costs	(825)	(949)
Total debt	$80,425	$80,301

Credit Facilities

11. Long-term Debt

Debt consisted of the following at December 31, 2022 and 2021:

	As of December 31,
	2022	2021
PNC Facility	$81,250	$65,000
Total	81,250	65,000
Unamortized debt issuance costs	(949)	(1,306)
Total debt	$80,301	$63,694

Credit Facilities

Truist Term Loans and Revolver

PNC Loan Facility

On April 30, 2021, the Company entered into a $5.0 million revolving line of credit agreement (“PNC Line of Credit”). The PNC Line of Credit has an expiration date of April 30, 2024 and bears interest at a rate per annum equal to the sum of the daily LIBOR rate plus 1.65% or an alternate base rate plus .65% and is due on the first day of each month beginning June 1, 2021. Any outstanding principal and accrued interest will be due on the expiration date. Beginning July 1, 2021, quarterly bank fees equal to 1.65% per day per annum will be due in arrears and will continue on the first day of each quarter thereafter. All debt related to the PNC Line of Credit is collateralized by the Company’s assets. The Company is also subject to 0.20% unused line fee calculated per annum on the unused balance of the PNC Line of Credit.

The PNC Loan Facility and PNC Line of Credit nonfinancial covenants include restrictions related to unpermitted property liens and the requirement of audited financial statements. Both agreements also contain several financial covenants, including the following ratios: accounts receivable default, delinquency, dilution, days sales outstanding, leverage, and fixed charge coverage. As of December 31, 2022, the Company was in compliance with all financial and nonfinancial debt covenants as required by both loan agreements.

Interest expense on long-term debt in 2022, 2021, and 2020, including amortization of debt issuance costs, was $3.4 million, $1.4 million, and $1.1 million, respectively.

Supplemental Condensed Balance Sheet Information (Q3) (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Schedule of Other Receivables

Other receivables consisted of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
Rebates receivable	$36,556	$27,955
Other	191	246
Total other receivables	$36,747	$28,201

Schedule of Inventory

Inventory consisted of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
Intravenous drugs	$27,508	$25,674
Oral pharmaceuticals	10,336	10,802
Total inventories	$37,844	$36,476

Inventories consisted of the following at December 31, 2022 and 2021:

	As of December 31,
	2022	2021
Intravenous drugs	$25,674	$28,897
Oral pharmaceuticals	10,802	5,632
Total inventories	$36,476	$34,529

Schedule of Property and Equipment, net

Property and equipment, net consisted of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
Leasehold improvements	$30,078	$26,076
Furniture, fixtures and equipment	2,722	2,669
Medical equipment	12,659	11,003
Computer equipment	3,325	3,115
Signs	147	129
Automobiles	59	69
Software	4,412	4,834
Construction-in-progress	6,150	1,433
Property and equipment, gross	59,552	49,328
Accumulated depreciation and amortization	(23,312)	(17,348)
Property and equipment, net	$36,240	$31,980

Property and equipment, net, consisted of the following at December 31, 2022 and 2021:

	As of December 31,
	2022	2021
Leasehold improvements	$26,076	$23,744
Furniture, fixtures and equipment	2,669	2,346
Medical equipment	11,003	8,811
Computer equipment	3,115	2,713
Signs	129	117
Automobiles	69	69
Software	4,834	4,036
Construction-in-progress	1,433	1,445
	49,328	43,281
Accumulated depreciation and amortization	(17,348)	(10,633)
Property and equipment, net	$31,980	$32,648

Schedule of Other Accrued Liabilities, Current

Accrued other consisted of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
Refund liability	$14,521	$14,544
Deferred social security taxes - COVID	—	378
Excise taxes payable	2,700	—
Current portion of finance lease liabilities	630	425
Other	5,126	2,453
Total accrued other	$22,977	$17,800

Condensed Consolidated Statements of Cash Flows (Parenthetical) (Q3) - USD ($)
$ in Thousands

9 Months Ended

12 Months Ended

Sep. 30, 2023

Sep. 30, 2022

Dec. 31, 2022

Dec. 31, 2021

Dec. 31, 2020

Amortization of operating right-of-use assets

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$ (1,446)

$ (1,995)

[1]	Includes related party amortization of operating right-of-use assets of $1,601 and $1,536 for the nine months ended September 30, 2023 and 2022, respectively.
[2]	Includes related party amortization of operating right-of-use assets of $2,059 for the year ended December 31, 2022
[3]	Includes changes in related party balances of ($1,299) and $832 for the nine months ended September 30, 2023 and 2022, respectively.
[4]	Includes changes in related party balances of ($1,850), ($11,848) , and ($6,322) for the years ended December 31, 2022, 2021, and 2020, respectively
[5]	Includes changes in related party balances of $10,627 and $23,309 for the nine months ended September 30, 2023 and 2022, respectively.
[6]	Includes changes in related party balances of $13,314, $23,309, and $37,744 for the years ended December 31, 2022, 2021 and 2020, respectively
[7]	Includes changes in related party balances of ($1,835) and ($1,446) for the nine months ended September 30, 2023 and 2022, respectively.
[8]	Includes changes in related party balance of ($1,995) for the year ended December 31, 2022

Commitments and Contingencies (FY) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Commitments and Contingencies [Abstract]
Period of initial term of agreement	5 years
Period of written notice to terminate agreement	12 months
Cost incurred under the agreement		$ 4.7	$ 18.7
Deposited additional security amount for payments under the agreement		$ 1.0

Leases - Right-of-use Assets And Lease Liabilities (Q3) (Details) - USD ($)
$ in Thousands

Sep. 30, 2023

Dec. 31, 2022

Dec. 31, 2021

Assets

Finance lease right-of-use assets, net (included in property and equipment, net)

$ 46,138

^[1]

$ 43,724

^[1],[2]

$ 0

^[2]

2,791

1,998

Total right-of-use assets

48,929

45,722

Current

Current portion of finance lease liabilities (included in accrued other)

7,123

^[3]

9,177

^[3],[4]

^[4]

630

425

Current portion of operating and finance lease liabilities

7,753

9,602

Long-term

Long-term finance lease liabilities (included in other long-term liabilities)

42,261

^[5]

37,224

^[5],[6]

$ 0

^[6]

2,126

1,619

Total lease liabilities

$ 52,140

$ 48,445

[1]	Includes related party operating right-of-use assets, net of $11,476 and $13,077 at September 30, 2023 and December 31, 2022, respectively
[2]	Includes related party operating lease right-of-use assets, net of $13,077 at December 31, 2022
[3]	Includes related party current portion of operating lease liabilities of $1,912 and $1,836 at September 30, 2023 and December 31, 2022, respectively
[4]	Includes related party current portion of operating lease liabilities of $1,836 at December 31, 2022
[5]	Includes related party long-term operating lease liabilities of $9,994 and $11,631 at September 30, 2023 and December 31, 2022, respectively
[6]	Includes related party long-term operating lease liabilities of $11,631 at December 31, 2022

Long-term Debt - Narrative (Q3) (Details)					9 Months Ended	12 Months Ended
Long-term Debt - Narrative (Q3) (Details)	Sep. 30, 2023 USD ($)	Feb. 14, 2022 USD ($)	Jul. 29, 2021 USD ($)	Apr. 30, 2021 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Aug. 15, 2022 USD ($)
PNC Loan Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 125,000,000	$ 75,000,000	$ 65,000,000
Pledged collateral				10,000,000
Proceeds from lines of credit			16,300,000	34,600,000
PNC Loan Facility \| Line of Credit
Debt Instrument [Line Items]
Proceeds from facility				34,600,000
Maximum borrowing capacity		125,000,000	$ 75,000,000	65,000,000
Pledged collateral				10,000,000
Quarterly collateral released				$ 2,500,000
Proceeds from lines of credit		16,300,000
Unamortized debt issuance costs	$ 400,000				$ 400,000
PNC Loan Facility \| Line of Credit \| Debt Instrument, Threshold Limit, Period One
Debt Instrument [Line Items]
Minimum funding threshold (in percent)	0.65			0.65
PNC Loan Facility \| Line of Credit \| Debt Instrument, Threshold Limit, Period Two
Debt Instrument [Line Items]
Minimum funding threshold (in percent)				0.75
PNC Loan Facility \| Line of Credit \| Alternate Base Rate
Debt Instrument [Line Items]
Basis spread (in percent)				1.45%
Revolving Credit Facility \| PNC Line of Credit \| Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 10,000,000		$ 5,000,000			$ 1,000,000
Bank fee (in percent)				1.65%
Unused line fee (in percent)				0.20%
Proceeds from lines of credit					$ 0	$ 0
Revolving Credit Facility \| PNC Line of Credit \| Line of Credit \| London Interbank Offered Rate (LIBOR) 1
Debt Instrument [Line Items]
Basis spread (in percent)				1.65%
Revolving Credit Facility \| PNC Line of Credit \| Line of Credit \| Alternate Base Rate
Debt Instrument [Line Items]
Basis spread (in percent)				0.65%
Revolving Credit Facility \| PNC Line of Credit \| Line of Credit \| Bloomberg Short-Term Bank Yield Index
Debt Instrument [Line Items]
Basis spread (in percent)		1.65%

Business Combinations (FY)

12 Months Ended

Dec. 31, 2022

Business Combinations [Abstract]

Business Combinations

5. Business Combinations

2022 Acquisitions

During the year ended December 31, 2022, the Company entered into a purchase agreement acquiring control of Northern Arizona Hematology and Oncology on January 1, 2022 for an aggregate purchase price of less than $0.1 million. Because the acquisition of Northern Arizona Hematology and Oncology was on the first day of the fiscal period, AON’s results for the year ended December 31, 2022 include the results of the acquired practice.

2021 Acquisitions

During 2021 the Company entered into Asset Purchase Agreements (“Transactions”) acquiring control of four (4) oncology practices. The Transactions allow the Company to expand domestic reach related to its comprehensive oncology and practice management services. As described in Note 3, the Company evaluated each of the Transactions and determined each acquisition represents a business combination. This standard also establishes principles and requirements for how the acquirer recognizes and measures in its financial statements the identifiable assets and goodwill acquired, the liabilities assumed, and any noncontrolling interest in the acquiree. ASC 805 also determines what information to disclose to enable users of the financial statements to evaluate the nature and financial effects of the business combination.

In connection with each of the Transactions, the Company acquired 100% of both the clinical and nonclinical assets of the respective seller. The clinical assets, acquired by AON Partners, primarily consist of medical supplies and drugs. Nonclinical assets, acquired by AOMC, primarily consist of tangible fixed assets and equipment. The following table summarizes the amounts of the assets acquired and consideration transferred recognized on respective acquisition dates disclosed in Note 1, the accounting for which is completed as of December 31, 2022. For the table below, the Company has presented the acquired locations collectively.

			2021 Acquired Locations
Purchase consideration
Cash transferred upon closing			$3,215
Assumed capital lease liabilities			1,097
Total consideration transferred			4,312
Net assets acquired
Inventories			2,211
Other assets			180
Property and equipment			1,371
Total net assets acquired			3,762
Amount assigned to goodwill			$550

2020 Acquisitions

During 2020 the Company entered into Transactions acquiring control of six (6) oncology practices. As described in Note 3, the Company evaluated each of the Transactions and determined each acquisition represents a business combination. This standard also establishes principles and requirements for how the acquirer recognizes and measures in its financial statements the identifiable assets and goodwill acquired, the liabilities assumed, and any noncontrolling interest in the acquiree. ASC 805 also determines what information to disclose to enable users of the financial statements to evaluate the nature and financial effects of the business combination.

In connection with each of the Transactions, the Company acquired 100% of both the clinical and nonclinical assets of the respective seller. The clinical assets, acquired by AON Partners, primarily consist of medical supplies and drugs. Nonclinical assets, acquired by AOMC, primarily consist of tangible fixed assets and equipment. The following table summarizes the amounts of the assets acquired and consideration transferred recognized on respective acquisition dates disclosed in Note 1. For the table below, the Company has presented the acquired locations collectively.

			2020 Acquired Locations
Purchase consideration
Cash transferred upon closing			$435
Issuance of note payable			621
Non-cash settlement			654
Total consideration transferred			1,710
Net assets acquired
Inventories			834
Property and equipment			360
Prepaids			16
Total net assets acquired			1,210
Amount assigned to goodwill			$500

	Pro Forma
	Year Ended December 31,
	2022	2021	2020
Revenue	$1,149,670	$1,033,187	$951,182
Net income	$2,589	$1,289	$22,381

From the dates of acquisition through December 31, 2022, December 31, 2021 and December 31, 2020, revenue attributable to 2022, 2021, and 2020 acquired businesses was $22.9 million, $55.7 million, and $63.1 million, respectively. It was impracticable to determine the effect on the Company’s net income (loss) of the acquired businesses as their operations have been integrated into the Company’s ongoing operations since the dates of acquisition.

In connection with each of the Transactions, the Company executed employment agreements with the selling physicians to become employees of AON Partners and/or Partners of Maryland. Additionally, for each transaction the Company and selling physicians entered into a separate unwind agreement granting each other a unilateral option that may be exercised by either party and effectively returns the acquired business to the selling physicians if exercised. In the event the Company or seller exercise their unwind rights, the selling physicians are required to repay the

original purchase price for the assets that were sold in the Transactions plus any assets that were acquired after the Transactions, less any accumulated depreciation or amortization with respect to the assets. The selling physicians are also required to assume all contracts associated with their practice. Additionally, in the event of unwind, the selling physicians are entitled to any severance amounts that are due to them under their employment agreement with AON Partners and their employment is terminated on the unwind date. As of December 31, 2022 and 2021, no liability has been recorded related to the unwind agreements as neither the Company nor any selling physicians have exercised their unwind rights and therefore no payments are considered probable to the selling physicians.

Long-term Debt (FY) (Tables)

12 Months Ended

Dec. 31, 2022

Long-term Debt

Debt consisted of the following at December 31, 2022 and 2021:

	As of December 31,
	2022	2021
PNC Facility	$81,250	$65,000
Total	81,250	65,000
Unamortized debt issuance costs	(949)	(1,306)
Total debt	$80,301	$63,694

Leases (Q3)

9 Months Ended

Sep. 30, 2023

10. Leases

The Company currently leases office facilities and equipment for its practices under noncancelable operating and finance lease agreements expiring on various dates through 2038. Certain of the leases contain renewal options which are exercisable at the Company’s discretion. These renewal options are considered in determining the lease

term if it is reasonably certain that the Company will exercise such options. Additionally, the Company leases certain other office and medical equipment under month-to-month lease agreements.

Right-of-use assets and lease liabilities consist of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
Assets
Operating lease right-of-use assets, net	$46,138	$43,724
Finance lease right-of-use assets, net (included in property and equipment, net)	2,791	1,998
Total right-of-use assets	$48,929	$45,722
Liabilities
Current
Current portion of operating lease liabilities	$7,123	$9,177
Current portion of finance lease liabilities (included in accrued other)	630	425
Long-term	7,753	9,602
Long-term operating lease liabilities	42,261	37,224
Long-term finance lease liabilities (included in other long-term liabilities)	2,126	1,619
Total lease liabilities	$52,140	$48,445

	Three Months Ended September 30,		Nine Months Ended September 30,
	2023	2022	2023	2022
Operating lease costs	$2,820	$3,161	$8,361	$9,297
Finance lease costs
Amortization of finance lease right-of-use assets	122	185	354	413
Interest on finance lease liabilities (included in interest expense)	35	19	79	60
Variable lease costs	560	862	1,742	2,232
Total lease costs	$3,537	$4,227	$10,536	$12,002

	Operating Lease	Finance Leases
2023 (remainder of year after September 30, 2023)	$1,679	$188
2024	10,940	753
2025	9,830	731
2026	9,413	492
2027	8,194	428
Thereafter	24,154	528
Total lease payments	64,210	3,120
Less: amount representing interest	(14,826)	(364)
Present value of lease liabilities	49,384	2,756
Less: current portion of lease liabilities	(7,123)	(630)
Long-term lease liabilities, net of current portion	$42,261	$2,126

The weighted-average remaining lease term as of September 30, 2023 and December 31, 2022 was 7.01 years and 5.68 years for operating leases and 5.00 years and 5.37 years for finance leases, respectively. The weighted-average discount rate as of September 30, 2023 and December 31, 2022 was 6.56% and 4.88% for operating leases and 5.12% and 3.60% for finance leases, respectively.

The cash paid for amounts included in the measurement of lease liabilities for the nine months ended September 30, 2023 and 2022 is as follows:

	Nine Months Ended September 30,
	2023	2022
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$7,678	$9,788
Operating cash flows from finance leases	79	60
Financing cash flows from finance leases	387	321
ROU assets obtained in exchange for new operating lease liabilities	9,862	9,771
ROU assets obtained in exchange for new finance lease liabilities	1,103	—

At September 30, 2023, the Company had entered into two sixty-month finance leases for medical equipment that had not yet commenced. The future commitments related to these leases are approximately $3.8 million and the Company expects to take control of the leased assets early in the fourth quarter.

10. Leases

term if it is reasonably certain that the Company will exercise such options. Additionally, the Company leases certain other office and medical equipment under month-to-month lease agreements.

Right-of-use assets and lease liabilities consist of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
Assets
Operating lease right-of-use assets, net	$46,138	$43,724
Finance lease right-of-use assets, net (included in property and equipment, net)	2,791	1,998
Total right-of-use assets	$48,929	$45,722
Liabilities
Current
Current portion of operating lease liabilities	$7,123	$9,177
Current portion of finance lease liabilities (included in accrued other)	630	425
Long-term	7,753	9,602
Long-term operating lease liabilities	42,261	37,224
Long-term finance lease liabilities (included in other long-term liabilities)	2,126	1,619
Total lease liabilities	$52,140	$48,445

	Three Months Ended September 30,		Nine Months Ended September 30,
	2023	2022	2023	2022
Operating lease costs	$2,820	$3,161	$8,361	$9,297
Finance lease costs
Amortization of finance lease right-of-use assets	122	185	354	413
Interest on finance lease liabilities (included in interest expense)	35	19	79	60
Variable lease costs	560	862	1,742	2,232
Total lease costs	$3,537	$4,227	$10,536	$12,002

	Operating Lease	Finance Leases
2023 (remainder of year after September 30, 2023)	$1,679	$188
2024	10,940	753
2025	9,830	731
2026	9,413	492
2027	8,194	428
Thereafter	24,154	528
Total lease payments	64,210	3,120
Less: amount representing interest	(14,826)	(364)
Present value of lease liabilities	49,384	2,756
Less: current portion of lease liabilities	(7,123)	(630)
Long-term lease liabilities, net of current portion	$42,261	$2,126

The cash paid for amounts included in the measurement of lease liabilities for the nine months ended September 30, 2023 and 2022 is as follows:

	Nine Months Ended September 30,
	2023	2022
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$7,678	$9,788
Operating cash flows from finance leases	79	60
Financing cash flows from finance leases	387	321
ROU assets obtained in exchange for new operating lease liabilities	9,862	9,771
ROU assets obtained in exchange for new finance lease liabilities	1,103	—

Subsequent Events (FY) (Details) - USD ($) $ in Thousands		12 Months Ended
Subsequent Events (FY) (Details) - USD ($) $ in Thousands	Feb. 23, 2023	Dec. 31, 2020
Subsequent Event [Abstract]
Number of new issued shares value		$ 28,500
Subsequent Event [Member] \| Investor [Member] \| Convertible Preferred Stock [Member] \| Minimum [Member]
Subsequent Event [Abstract]
Number of new issued shares value	$ 65,000

Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

Redeemable convertible preferred stock, shares outstanding (in shares)

Condensed Consolidated Balance Sheets (Q3) (Parenthetical)

Sep. 30, 2023

USD ($)

$ / shares

6,652,000

Operating lease right-of-use assets, net | $

$ 46,138,000

^[1]

Accounts payable | $

120,383,000

^[2]

Current portion of operating lease liabilities | $

7,123,000

^[3]

Long-term operating lease liabilities | $

$ 42,261,000

^[4]

Capital Unit, Class A

Capital Unit, Class A-1

Capital Unit, Class B

Current portion of operating lease liabilities | $

$ 11,476,000

Accounts payable | $

112,740,000

1,912,000

Long-term operating lease liabilities | $

$ 9,994,000

Series A Preferred Stock

Par value (dollars per share) | $ / shares

$ 0.0001

Shares authorized (shares)

7,500,000

Shares issued (in shares)

6,651,610

Redeemable convertible preferred stock, shares outstanding (in shares)

6,651,610

Liquidation preference | $

$ 66,649,130

Common Class A

Common stock, par value (in usd per share) | $ / shares

$ 0.0001

Common stock, shares authorized (in shares)

200,000,000

Common stock, shares issued (in shares)

9,453,604

Common stock, par value (in usd per share) | $ / shares

9,453,604

Common Class B

$ 0.0001

Common stock, shares authorized (in shares)

100,000,000

Common stock, shares issued (in shares)

25,109,551

25,109,551

[1]	Includes related party operating right-of-use assets, net of $11,476 and $13,077 at September 30, 2023 and December 31, 2022, respectively
[2]	Includes amounts due to related party of $112,740 and $102,113 at September 30, 2023 and December 31, 2022, respectively
[3]	Includes related party current portion of operating lease liabilities of $1,912 and $1,836 at September 30, 2023 and December 31, 2022, respectively
[4]	Includes related party long-term operating lease liabilities of $9,994 and $11,631 at September 30, 2023 and December 31, 2022, respectively

Summary of Significant Accounting Policies and Basis of Presentation, Offering Costs (FY) (Details) $ in Millions	Dec. 31, 2022 USD ($)
Offering Costs [Abstract]
Offering costs	$ 0.3

Related Parties, Leases (FY) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Cash paid for leases			$ 7,678	$ 9,788	$ 12,590
Related Party [Member]
Leases [Abstract]
Cash paid for leases	$ 600	$ 600	$ 1,900	$ 1,900	$ 2,500	$ 2,300	$ 6,800

Variable Interest Entities (Q3)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Variable Interest Entities

4. Variable Interest Entities

AOMC, AON Partners, and Partners of Maryland. The responsibilities of AOMC include, but are not limited to, negotiating provider and payor contracts, employment and compensation decisions, billing and collections, furnishing all supplies and equipment necessary for the respective practice’s operations as well as, necessary real estate, contracting on behalf of AON Partners and Partners of Maryland, entering into leases, holding a power of attorney to perform the above activities, preparing, maintaining and administering all accounting records (including financial reporting), expense payment, and maintenance of all information systems/software. AON LLC is paid a management fee to compensate AOMC for the services provided. AON Central Services is 80% physician owned and 20% owned by AON LLC. AOMC entered into an agreement with AON Central Services, effective January 1, 2023, to provide qualified non-clinical and non-medical employees to AOMC to support the operation of the physician practices. AOMC pays a monthly management fee to AON Central Services equal to the aggregate cost of compensation, benefits and all other costs related to these employees. AON LLC invested $0.2 million in MIBA, a newly formed LLC, during the second quarter of 2023 in exchange for 56% equity ownership. The Company evaluated AON LLC’s relationship with MIBA under the VIE model and determined it was a VIE and the Company is the primary beneficiary based on its financial controlling interest.

Based on various quantitative and qualitative factors, including assessment of certain services performed and relationships held above, management has determined that AON Partners, Partners of Maryland, AON Central Services, and MIBA are all variable interest entities and AOMC is the primary beneficiary who holds the decision-making rights over the activities that most significantly impact the economic performance of AON Partners, Partners of Maryland, AON Central Services, and MIBA through the MSAs and other contractual agreements. Accordingly, the results of AON Partners, Partners of Maryland, AON Central Services, and MIBA have been consolidated with the Company for the three and nine month periods ended September 30, 2023 and 2022.

The assets of AON Partners, Partners of Maryland, AON Central Services, and MIBA as of September 30, 2023 and December 31, 2022, are as follows:

	As of September 30, 2023	As of December 31, 2022
Assets
Cash and cash equivalents	$33,083	$26,844
Accounts receivable	141,039	136,098
Inventories	37,844	36,476
Prepaid expenses and other current assets	869	846
Goodwill and intangibles, net	180	180
Other receivables	36,294	28,139
Other assets	2,014	1,489
Total assets	$251,323	$230,072

The liabilities of AON Partners, Partners of Maryland, AON Central Services, and MIBA as of September 30, 2023 and December 31, 2022, are as follows:

	As of September 30, 2023	As of December 31, 2022
Liabilities
Accounts payable	$114,779	$102,783
Accrued compensation and benefits	22,747	6,021
Accrued other	16,038	15,926
Other long-term liabilities	137	452
Due to AON LLC and subsidiaries, net	134,344	128,204
Total liabilities	$288,045	$253,386

All intercompany transactions and balances with the VIEs are eliminated in consolidation.

4. Variable Interest Entities

AOMC is a wholly owned subsidiary of AON LLC and neither AOMC nor AON LLC has ownership interest in AON Partners and Partners of Maryland. Both AON Partners and Partners of Maryland are fully owned by a physician. AON LLC operates its physician practices through the MSAs and other contractual agreements between AOMC, AON Partners, and Partners of Maryland. The responsibilities of AOMC include, but are not limited to negotiating provider and payor contracts, employment and compensation decisions, billing and collections, furnishing all supplies and equipment necessary for the respective practice’s operations as well as, necessary real estate, contracting on behalf of AON Partners and Partners of Maryland, entering into leases, holding a power of attorney to perform the above activities, preparing, maintaining and administering all accounting records (including financial reporting), expense payment, and maintenance of all information systems/software. AON LLC is paid a management fee to compensate AOMC for the services provided.

Based on various quantitative and qualitative factors, including assessment of certain services performed and relationships held above, management has determined that AON Partners and Partners of Maryland are both variable interest entities and AOMC is the primary beneficiary who holds the decision-making rights over the activities that most significantly impact AON Partners and Partners of Maryland’s economic performance through the MSAs and other contractual agreements. Accordingly, the results of AON Partners and Partners of Maryland have been consolidated with the Company for the years ended December 31, 2022, 2021, and 2020.

The assets of AON Partners and Partners of Maryland as of December 31, 2022 and 2021, are as follows:

	As of December 31,
Assets	2022	2021
Cash and cash equivalents	$26,844	$24,074
Accounts receivable	136,098	111,183
Inventories	36,476	34,529
Property and equipment, net	—	108
Prepaid expenses and other current assets	846	374
Goodwill and intangibles, net	180	180
Other receivables	28,139	24,950
Other assets	1,489	1,241
Total assets	$230,072	$196,639

The liabilities of AON Partners and Partners of Maryland as of December 31, 2022 and 2021, are as follows:

	As of December 31,
Liabilities	2022	2021
Accounts payable	$102,783	$89,275
Accrued compensation and benefits	6,021	6,504
Accrued other	15,926	9,346
Medicare advance payment	—	3,742
Other long-term liabilities	452	81
Due to AON and subsidiaries, net	128,204	102,090
Total liabilities	$253,386	$211,038

All intercompany transactions and balances with the VIEs are eliminated in consolidation.

Income Taxes (Q3) (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
Income Taxes (Q3) (Details) - USD ($)	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Taxes [Abstract]
Effective income tax rate (in percent)	(1.10%)	0.00%	(0.80%)	0.00%	0.00%	129.33%	(3.71%)
Income tax expense	$ 315,000	$ 0	$ 315,000	$ 0	$ 0	$ 460,000	$ (783,000)

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Financial Assets Measured at Fair Value on Recurring Basis

Fair Value Measurements (FY) (Tables)

12 Months Ended

Dec. 31, 2022

Fair Value Measurements [Abstract]

The following table summarizes the Company’s financial assets that are measured at fair value on a recurring basis:

	As of December 31, 2022
	Amortized Cost	Gross Unrealized Gains	Gross Unrealized Losses	Estimated Fair Value
Cash equivalents⁽¹⁾
Level 1:
Money market funds	$109	$—	$—	$109
Marketable securities
Level 2:
Corporate bonds	7,742	6	(125)	7,623
U.S. Treasury securities	2,226	6	(4)	2,228
Level 2 total	9,968	12	(129)	9,851
Total	$10,077	$12	$(129)	$9,960

Remaining Contractual Maturities

The fair value of the Company’s marketable securities as of December 31, 2022, by remaining contractual maturities, were as follows:

	As of December 31, 2022
	Corporate Bonds	U.S. Treasury Securities	Total
Due within one year	$3,660	$1,073	$4,733
Due within one to five years	3,963	1,155	5,118
Total	$7,623	$2,228	$9,851

Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 30, 2023
Cover [Abstract]
Document Type	S-1/A
Amendment Flag	false
Entity Registrant Name	American Oncology Network, Inc.
Entity Central Index Key	0001839998
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false

Marketable Securities (Q3) (Tables)

9 Months Ended

Sep. 30, 2023

Investments, Debt and Equity Securities [Abstract]

Debt Securities, Available-for-Sale

The following table summarizes the Company’s marketable securities financial assets that are measured at fair value on a recurring basis:

	As of September 30, 2023
	Amortized Cost	Gross Unrealized Gains	Gross Unrealized Losses	Estimated Fair Value
Cash equivalents⁽¹⁾
Level 1:
Overnight repurchase agreements⁽²⁾	$28,272	$—	$—	$28,272
Money market funds	773	—	—	773
U.S. Treasury Bills	18,606	—	—	18,606
Level 1 total	$47,651	$—	$—	$47,651
Marketable securities
Level 2:
Corporate bonds	13,980	62	(38)	14,004
U.S. Treasury securities	11,981	52	(4)	12,029
Level 2 total	25,961	114	(42)	26,033
Total	$73,612	$114	$(42)	$73,684

	As of December 31, 2022
	Amortized Cost	Gross Unrealized Gains	Gross Unrealized Losses	Estimated Fair Value
Cash equivalents⁽¹⁾
Level 1:
Money market funds	$109	$—	$—	$109
Marketable securities
Level 2:
Corporate bonds	7,742	6	(125)	7,623
U.S. Treasury securities	2,226	6	(4)	2,228
Level 2 total	9,968	12	(129)	9,851
Total	$10,077	$12	$(129)	$9,960

(1)	Included in cash and cash equivalents in the Consolidated Balance Sheets at September 30, 2023 and December 31, 2022.

(2)

The fair value of the Company’s marketable securities as of September 30, 2023, by remaining contractual maturities, were as follows:

	Corporate Bonds	U.S. Treasuries	Total
Due in one year or less	$4,805	$8,385	$13,190
Due in one to five years	9,199	3,644	12,843
Total	$14,004	$12,029	$26,033

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Notes receivable, amortization period (in months)

Fair Value Measurements, Remaining Contractual Maturities (FY) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Remaining Contractual Maturities [Abstract]
Estimated Fair Value	$ 26,034	$ 9,851
Marketable Securities [Member]
Remaining Contractual Maturities [Abstract]
Due within one year		4,733
Due within one to five years		5,118
Estimated Fair Value		9,851
Corporate Bonds [Member]
Remaining Contractual Maturities [Abstract]
Due within one year		3,660
Due within one to five years		3,963
Estimated Fair Value		7,623
U.S. Treasury Securities [Member]
Remaining Contractual Maturities [Abstract]
Due within one year		1,073
Due within one to five years		1,155
Estimated Fair Value		$ 2,228

Related Parties - Narrative (Q3) (Details)
$ in Thousands

3 Months Ended

9 Months Ended

12 Months Ended

Sep. 30, 2023

USD ($)

office

Sep. 30, 2022

USD ($)

Sep. 30, 2023

USD ($)

office

Sep. 30, 2022

USD ($)

Dec. 31, 2022

USD ($)

Dec. 31, 2021

USD ($)

Dec. 31, 2020

USD ($)

60 months

Incremental borrowing rate

7.14%

1.57%

Payments for operating leases

$ 7,678

$ 9,788

$ 12,590

Notes receivable, amortization period (in months)

$ 310,894

^[1]

$ 267,647

^[1]

$ 880,827

^[1]

780,658

^[1]

$ 1,054,217

^[2],[3]

$ 865,788

^[2],[3]

$ 658,638

^[2],[3]

60 months

Number of offices with operating lease | office

Payments for operating leases

$ 600

600

$ 1,900

1,900

$ 2,500

$ 2,300

$ 6,800

271,790

236,077

777,478

682,671

268,000

$ 239,000

774,000

$ 682,000

Concentration risk (in percentage)

$ 113,000

$ 102,100

86.00%

89.00%

88.00%

86.00%

Concentration risk (in percentage)

94.00%

[1]	Includes related party inventory expense of $271,790 and $236,077 and $777,478 and $682,671 for the three and nine months ended September 30, 2023 and 2022, respectively.
[2]	Includes related party inventory expense of $922,148, $718,675, and $567,782 for the years ended December 31, 2022, 2021, and 2020, respectively
[3]	Includes related party rent expense of $2,643, $2,319, and $6,845 for the years ended December 31, 2022, 2021 and 2020, respectively

Related Parties (FY)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Related Parties

11. Related Parties

Transactions Notes Receivable

	As of September 30, 2023	As of December 31, 2022	Original Principal	Issue Date	Maturity Date
Notes receivable
Note 2	$1,027	$1,057	$5,355	5/1/2019	4/30/2024
Note 3	42	119	491	6/1/2019	5/31/2024
Note 6	—	351	1,111	5/22/2020	5/22/2023
Note 8	2,065	2,221	2,816	5/1/2020	5/1/2025
Note 9	—	125	125	1/24/2022	6/30/2023
Total notes receivables	3,134	3,873
Less: Current portion of notes receivable	$(1,630)	(1,797)
Notes receivable, less current portion	$1,504	$2,076

Leases

Inventory Purchases/Concentration Risk

14. Related Parties

Transactions Notes Receivable

	As of December 31,		Original Principal	Issue Date	Maturity Date
	2022	2021	Original Principal	Issue Date	Maturity Date
Notes receivable
Note 2	$1,057	$1,294	$5,355	5/1/2019	4/30/2024
Note 3	119	217	491	6/1/2019	5/31/2024
Note 4	—	259	917	8/1/2019	7/31/2024
Note 6	351	680	1,111	5/22/2020	5/22/2023
Note 8	2,221	2,513	2,816	5/1/2020	5/1/2025
Note 9	125	—	125	1/24/2022	6/30/2023
Total notes receivables	3,873	4,963
Less: Current portion of notes receivable	(1,797)	(1,812)
Notes receivable, less current portion	$2,076	$3,151

Leases

Inventory Purchases/Concentration Risk

Summary of Significant Accounting Policies and Basis of Presentation, Accounts Receivable (FY) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2023	Dec. 31, 2020
Accounts Receivable [Abstract]
Accounts receivable, net	$ 136,098	$ 111,226	$ 141,039	$ 80,400
Accounts Receivable [Member] \| Credit Concentration Risk [Member]
Accounts Receivable [Abstract]
Percentage of account receivables	100.00%	100.00%
Accounts Receivable [Member] \| Credit Concentration Risk [Member] \| Medicare [Member]
Accounts Receivable [Abstract]
Percentage of account receivables	25.00%	27.00%
Accounts Receivable [Member] \| Credit Concentration Risk [Member] \| Managed Medicare [Member]
Accounts Receivable [Abstract]
Percentage of account receivables	25.00%	21.00%
Accounts Receivable [Member] \| Credit Concentration Risk [Member] \| Other Commercial [Member]
Accounts Receivable [Abstract]
Percentage of account receivables	17.00%	17.00%
Accounts Receivable [Member] \| Credit Concentration Risk [Member] \| BCBS [Member]
Accounts Receivable [Abstract]
Percentage of account receivables	17.00%	16.00%
Accounts Receivable [Member] \| Credit Concentration Risk [Member] \| Managed Medicaid [Member]
Accounts Receivable [Abstract]
Percentage of account receivables	8.00%	12.00%
Accounts Receivable [Member] \| Credit Concentration Risk [Member] \| Other [Member]
Accounts Receivable [Abstract]
Percentage of account receivables	8.00%	7.00%

Business Combinations (Q3)	9 Months Ended
Business Combinations (Q3)	Sep. 30, 2023
Business Combination and Asset Acquisition [Abstract]
Business Combinations	5. Business Combinations 2022 Acquisitions During the nine months ended September 30, 2022, the Company entered into a purchase agreement acquiring control of Northern Arizona Hematology and Oncology on January 1, 2022 for an aggregate purchase price of less than $0.1 million. Because the acquisition of Northern Arizona Hematology and Oncology was on the first day of the fiscal period, the Company’s results for the three and nine months ended September 30, 2022 include the results of the acquired practice. In connection with each of the Company’s business combinations (the “Transactions”), the Company executed employment agreements with the selling physicians to become employees of AON Partners and/or Partners of Maryland. Additionally, for each transaction the Company and selling physicians entered into a separate unwind agreement granting each other a unilateral option that may be exercised by either party and effectively returns the acquired business to the selling physicians if exercised. In the event the Company or seller exercise their unwind rights, the selling physicians are required to repay the original purchase price for the assets that were sold in the Transaction plus any assets that were acquired after the Transaction, less any accumulated depreciation or amortization with respect to the assets. The selling physicians are also required to assume all contracts associated with their practice. Additionally, in the event of unwind, the selling physicians are entitled to any severance amounts that are due to them under their employment agreement with AON Partners and their employment is terminated on the unwind date. As of September 30, 2023 and December 31, 2022, no liability has been recorded related to the unwind agreements as neither the Company nor any selling physicians have exercised their unwind rights and therefore no payments are considered probable to the selling physicians.

Marketable Securities (Q3) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-Sale [Line Items]
Cash and cash equivalents	$ 51,653	$ 26,926	$ 27,354
Gross Unrealized Gains	114	12
Gross Unrealized Losses	(42)	(129)
Estimated Fair Value	26,034	9,851
Cash and cash equivalents and available-for-sale securities, amortized cost	73,612	10,077
Cash and cash equivalents and marketable securities, aggregate fair value	73,684	9,960
Level 1
Debt Securities, Available-for-Sale [Line Items]
Cash and cash equivalents	47,651
Cash and cash equivalents, aggregate fair value	47,651
Level 1 \| U.S. Treasury securities
Debt Securities, Available-for-Sale [Line Items]
Cash and cash equivalents	18,606
Cash and cash equivalents, aggregate fair value	18,606
Level 1 \| Overnight Repurchase Agreements
Debt Securities, Available-for-Sale [Line Items]
Cash and cash equivalents	28,272
Cash and cash equivalents, aggregate fair value	28,272
Level 1 \| Money market funds
Debt Securities, Available-for-Sale [Line Items]
Cash and cash equivalents	773	109
Cash and cash equivalents, aggregate fair value	773	109
Level 2
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	25,961	9,968
Gross Unrealized Gains	114	12
Gross Unrealized Losses	(42)	(129)
Estimated Fair Value	26,033	9,851
Level 2 \| Corporate bonds
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	13,980	7,742
Gross Unrealized Gains	62	6
Gross Unrealized Losses	(38)	(125)
Estimated Fair Value	14,004	7,623
Level 2 \| U.S. Treasury securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	11,981	2,226
Gross Unrealized Gains	52	6
Gross Unrealized Losses	(4)	(4)
Estimated Fair Value	$ 12,029	$ 2,228

Variable Interest Entities (FY) (Details) - USD ($)
$ in Thousands

Sep. 30, 2023

Dec. 31, 2022

Dec. 31, 2021

Dec. 31, 2020

Assets [Abstract]

$ 51,653

$ 26,926

$ 27,354

Accounts receivable

141,039

136,098

111,226

$ 80,400

37,844

36,476

34,529

31,980

32,648

3,445

2,670

3,277

1,230

1,112

36,747

28,201

25,078

7,055

5,199

3,111

394,014

326,228

248,298

Liabilities [Abstract]

Accrued compensation and benefits

120,383

^[1]

106,495

^[1],[2]

92,908

^[2]

16,210

7,466

8,901

22,977

17,800

13,792

3,742

10,333

5,749

5,717

AON Partners and Partners of Maryland [Member]

$ 300,923

264,212

188,754

Assets [Abstract]

26,844

24,074

Accounts receivable

136,098

111,183

36,476

34,529

108

846

374

180

28,139

24,950

1,489

1,241

230,072

196,639

Liabilities [Abstract]

Accrued compensation and benefits

102,783

89,275

6,021

6,504

15,926

9,346

3,742

Due to AON and subsidiaries, net

452

128,204

102,090

Variable Interest Entities [Abstract]

$ 253,386

$ 211,038

[1]	Includes amounts due to related party of $112,740 and $102,113 at September 30, 2023 and December 31, 2022, respectively
[2]	Includes amounts due to related party of $102,113 and $88,799 at December 31, 2022 and 2021, respectively

Variable Interest Entities (FY)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Variable Interest Entities

4. Variable Interest Entities

The assets of AON Partners, Partners of Maryland, AON Central Services, and MIBA as of September 30, 2023 and December 31, 2022, are as follows:

	As of September 30, 2023	As of December 31, 2022
Assets
Cash and cash equivalents	$33,083	$26,844
Accounts receivable	141,039	136,098
Inventories	37,844	36,476
Prepaid expenses and other current assets	869	846
Goodwill and intangibles, net	180	180
Other receivables	36,294	28,139
Other assets	2,014	1,489
Total assets	$251,323	$230,072

The liabilities of AON Partners, Partners of Maryland, AON Central Services, and MIBA as of September 30, 2023 and December 31, 2022, are as follows:

	As of September 30, 2023	As of December 31, 2022
Liabilities
Accounts payable	$114,779	$102,783
Accrued compensation and benefits	22,747	6,021
Accrued other	16,038	15,926
Other long-term liabilities	137	452
Due to AON LLC and subsidiaries, net	134,344	128,204
Total liabilities	$288,045	$253,386

All intercompany transactions and balances with the VIEs are eliminated in consolidation.

4. Variable Interest Entities

Based on various quantitative and qualitative factors, including assessment of certain services performed and relationships held above, management has determined that AON Partners and Partners of Maryland are both variable interest entities and AOMC is the primary beneficiary who holds the decision-making rights over the activities that most significantly impact AON Partners and Partners of Maryland’s economic performance through the MSAs and other contractual agreements. Accordingly, the results of AON Partners and Partners of Maryland have been consolidated with the Company for the years ended December 31, 2022, 2021, and 2020.

The assets of AON Partners and Partners of Maryland as of December 31, 2022 and 2021, are as follows:

	As of December 31,
Assets	2022	2021
Cash and cash equivalents	$26,844	$24,074
Accounts receivable	136,098	111,183
Inventories	36,476	34,529
Property and equipment, net	—	108
Prepaid expenses and other current assets	846	374
Goodwill and intangibles, net	180	180
Other receivables	28,139	24,950
Other assets	1,489	1,241
Total assets	$230,072	$196,639

The liabilities of AON Partners and Partners of Maryland as of December 31, 2022 and 2021, are as follows:

	As of December 31,
Liabilities	2022	2021
Accounts payable	$102,783	$89,275
Accrued compensation and benefits	6,021	6,504
Accrued other	15,926	9,346
Medicare advance payment	—	3,742
Other long-term liabilities	452	81
Due to AON and subsidiaries, net	128,204	102,090
Total liabilities	$253,386	$211,038

All intercompany transactions and balances with the VIEs are eliminated in consolidation.

Related Parties, Transactions Notes Receivable (FY) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Transactions Notes Receivable [Abstract]
Amortized period for note receivable	60 months
Notes Receivable Net [Abstract]
Total notes receivables	$ 3,134	$ 3,873
Less: Current portion of notes receivable	(1,630)	(1,797)	$ (1,812)
Notes receivable, less current portion	$ 1,504	$ 2,076	$ 3,151
Related Party [Member]
Transactions Notes Receivable [Abstract]
Amortized period for note receivable		60 months
Incremental borrowing rate		1.57%	1.55%
Notes Receivable Net [Abstract]
Total notes receivables		$ 3,873	$ 4,963
Less: Current portion of notes receivable		(1,797)	(1,812)
Notes receivable, less current portion		2,076	3,151
Note 2 [Member] \| Related Party [Member]
Notes Receivable Net [Abstract]
Total notes receivables		1,057	1,294
Original Principal		$ 5,355
Issue Date		May 01, 2019
Maturity Date		Apr. 30, 2024
Note 3 [Member] \| Related Party [Member]
Notes Receivable Net [Abstract]
Total notes receivables		$ 119	217
Original Principal		$ 491
Issue Date		Jun. 01, 2019
Maturity Date		May 31, 2024
Note 4 [Member] \| Related Party [Member]
Notes Receivable Net [Abstract]
Total notes receivables		$ 0	259
Original Principal		$ 917
Issue Date		Aug. 01, 2019
Maturity Date		Jul. 31, 2024
Note 6 [Member] \| Related Party [Member]
Notes Receivable Net [Abstract]
Total notes receivables		$ 351	680
Original Principal		$ 1,111
Issue Date		May 22, 2020
Maturity Date		May 22, 2023
Note 8 [Member] \| Related Party [Member]
Notes Receivable Net [Abstract]
Total notes receivables		$ 2,221	2,513
Original Principal		$ 2,816
Issue Date		May 01, 2020
Maturity Date		May 01, 2025
Note 9 [Member] \| Related Party [Member]
Notes Receivable Net [Abstract]
Total notes receivables		$ 125	$ 0
Original Principal		$ 125
Issue Date		Jan. 24, 2022
Maturity Date		Jun. 30, 2023

Long-term Debt, Credit Facilities (FY) (Details) - USD ($) $ in Thousands					1 Months Ended	12 Months Ended
	Jul. 29, 2021	Apr. 30, 2021	Sep. 04, 2020	Apr. 22, 2019	Aug. 31, 2018	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Aug. 15, 2022	Feb. 14, 2022
Debt Instruments [Abstract]
Restricted cash						$ 0	$ 5,000
Debt issuance cost						300
Loss on extinguishment of debt						$ 0	(80)	$ 0
Truist Revolver [Member]
Debt Instruments [Abstract]
Long-term debt, term						1 year
Revolving line of credit agreement amount			$ 10,000	$ 27,000	$ 10,000
Line of credit maturity date				Apr. 20, 2020	Aug. 31, 2019	Sep. 03, 2021
Borrowings outstanding							0
Truist Revolver [Member] \| LIBOR [Member]
Debt Instruments [Abstract]
Term of variable rate						1 month
Basis spread on interest rate					1.30%
Truist Revolver [Member] \| LIBOR [Member] \| Minimum [Member]
Debt Instruments [Abstract]
Basis spread on interest rate			3.60%
Truist Revolver [Member] \| LIBOR [Member] \| Maximum [Member]
Debt Instruments [Abstract]
Basis spread on interest rate			4.35%
PNC Line of Credit [Member]
Debt Instruments [Abstract]
Revolving line of credit agreement amount		$ 5,000							$ 1,000	$ 10,000
Line of credit maturity date						Apr. 30, 2024
Proceeds from lines of credit						$ 0	0
Percentage of quarterly bank fees		1.65%
Percentage of unused line fee		0.20%
PNC Line of Credit [Member] \| LIBOR [Member]
Debt Instruments [Abstract]
Basis spread on interest rate		1.65%
PNC Line of Credit [Member] \| Alternate Base Rate [Member]
Debt Instruments [Abstract]
Basis spread on interest rate		0.65%
PNC Line of Credit [Member] \| Bloomberg Short-Term Bank Yield Index [Member]
Debt Instruments [Abstract]
Basis spread on interest rate	1.65%
Truist Term Loans [Member]
Debt Instruments [Abstract]
Long-term debt, term						7 years
Long-term debt, interest only term						2 years
Long-term debt, principal and interest payments term						5 years
PNC Loan Facility [Member]
Debt Instruments [Abstract]
Line of credit maturity date						Apr. 30, 2024
Proceeds from lines of credit	$ 16,300	$ 34,600
Line of credit facility, maximum borrowing capacity	$ 75,000	$ 65,000								$ 125,000
Percentage of borrowing base facility limit in first year		65.00%
Percentage of borrowing base facility limit in subsequent years		75.00%
Pledged collateral as restricted cash		$ 10,000
Pledged collateral as restricted cash to be released quarterly in increments		$ 2,500
Restricted cash							5,000
Debt issuance cost						$ 300	1,100
Loss on extinguishment of debt							(100)
Interest expense on long-term debt						$ 3,400	$ 1,400	$ 1,100
PNC Loan Facility [Member] \| LIBOR [Member]
Debt Instruments [Abstract]
Term of variable rate						1 month
PNC Loan Facility [Member] \| Alternate Base Rate [Member]
Debt Instruments [Abstract]
Basis spread on interest rate		1.45%

Related Parties (Q3) (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Schedule of Related Party Transactions

	As of September 30, 2023	As of December 31, 2022	Original Principal	Issue Date	Maturity Date
Notes receivable
Note 2	$1,027	$1,057	$5,355	5/1/2019	4/30/2024
Note 3	42	119	491	6/1/2019	5/31/2024
Note 6	—	351	1,111	5/22/2020	5/22/2023
Note 8	2,065	2,221	2,816	5/1/2020	5/1/2025
Note 9	—	125	125	1/24/2022	6/30/2023
Total notes receivables	3,134	3,873
Less: Current portion of notes receivable	$(1,630)	(1,797)
Notes receivable, less current portion	$1,504	$2,076

The notes bear interest at the Company’s incremental borrowing rate (1.57% at December 31, 2022 and 1.55% at December 31, 2021).

	As of December 31,		Original Principal	Issue Date	Maturity Date
	2022	2021	Original Principal	Issue Date	Maturity Date
Notes receivable
Note 2	$1,057	$1,294	$5,355	5/1/2019	4/30/2024
Note 3	119	217	491	6/1/2019	5/31/2024
Note 4	—	259	917	8/1/2019	7/31/2024
Note 6	351	680	1,111	5/22/2020	5/22/2023
Note 8	2,221	2,513	2,816	5/1/2020	5/1/2025
Note 9	125	—	125	1/24/2022	6/30/2023
Total notes receivables	3,873	4,963
Less: Current portion of notes receivable	(1,797)	(1,812)
Notes receivable, less current portion	$2,076	$3,151

Business (Q3) (Details)
$ / shares in Units, $ in Thousands

3 Months Ended

9 Months Ended

12 Months Ended

Sep. 20, 2023

USD ($)

$ / shares

Sep. 30, 2023

USD ($)

state

$ / shares

Sep. 30, 2022

USD ($)

Sep. 30, 2023

USD ($)

practice

state

$ / shares

Sep. 30, 2022

USD ($)

Dec. 31, 2022

USD ($)

OncologyPractice

Dec. 31, 2021

Number of oncology practices

Number of states in which entity operates | state

Reverse recapitalization, equity conversion ratio

Number of securities called by each warrant (in shares)

Transaction expenses | $

$ 13,000

$ 24,603

^[1]

$ 151

^[1]

$ 29,886

$ 151

Sponsor Earnout Shares

Earnout period (in years)

5 years

Percentage of stock subject to vesting (in percent)

0.35

Number of shares subject to vesting (in shares)

2,839,375

Stock price trigger (in usd per share) | $ / shares

$ 13.5

Earnout period, trading days (in days)

20 days

Earnout period, threshold trading day period (in days)

30 days

Earnout period, number of months after closing (in months)

60 months

AON LLC

Reverse recapitalization costs | $

24,600

30,600

Transaction expenses | $

$ 24,600

$ 200

29,800

$ 200

Accrued transaction costs | $

$ 300

AON LLC | Temporary Equity

Adjustment to APIC, transaction costs | $

$ (800)

Common Class A

Shares issued (in shares)

1,047,343

19,495,376

9,453,604

Series A Preferred Stock

Stock price (in usd per share) | $ / shares

$ 10

Common Class B

4,703,628

Legacy AON Shareholders | Class B Prefunded Warrants

25,109,551

Legacy AON Shareholders | AON LLC

3,000,245

Legacy AON Shareholders | Common Class B

28,109,796

25,109,551

AON Inc. | AON LLC

AON Inc. | AON LLC | Series A Preferred Stock

9,532,354

Preferred units, outstanding (in units)

6,651,610

Digital Transformation Opportunities Corp. ("DTOC") | Common Class B

Reverse recapitalization, equity conversion ratio

DTOC Unredeemed Shareholders | Common Class A

DTOC Sponsor | Private Placement Warrants

147,511

DTOC Sponsor | Public Warrant

6,113,333

Warrant, exercise period, after initial public offering

8,337,500

12 months

Warrant, exercise period, after business combination

30 days

Warrant, term

5 years

DTOC Sponsor | Common Class A

Earnout shares not outstanding (in shares)

5,419,375

2,839,375

Stock price (in usd per share) | $ / shares

$ 11.5

DTOC Sponsor | Common Class A | Public Warrant

Number of securities called by each warrant (in shares)

AEA Growth Management LP | Series A Preferred Stock

Shares issued (in shares)

6,651,610

6,651,610

AON LLC

Reverse recapitalization, equity conversion ratio

AON LLC | Class B Prefunded Warrants

3,000,245

AON LLC | Common Class A

1,047,343

AON LLC | Common Class B

Stock price (in usd per share) | $ / shares

$ 0.01

AON LLC | Common Class B | Class B Prefunded Warrants

Number of securities called by each warrant (in shares)

[1]	Includes related party rent of $679 and $655 and $2,037 and $2,037 for the three and nine months ended September 30, 2023 and 2022, respectively.

Long-term Debt (Q3) (Tables)

9 Months Ended

Sep. 30, 2023

Schedule of Long-Term Debt Instruments

Debt consisted of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
PNC Facility	$81,250	$81,250
Total	81,250	81,250
Unamortized debt issuance costs	(825)	(949)
Total debt	$80,425	$80,301

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481568/470-20-55-69B

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69E
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481568/470-20-55-69E

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(a))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-3

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI https://asc.fasb.org//1943274/2147482925/835-30-45-2

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 10
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Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
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Other Receivables (FY)

12 Months Ended

Dec. 31, 2022

Other Receivables [Abstract]

Other Receivables

8. Other Receivables

Other receivables consisted of the following at December 31, 2022 and 2021:

	As of December 31,
	2022	2021
Rebates receivable	$27,955	$24,950
Other	246	128
Total other receivables	$28,201	$25,078

Supplemental Condensed Balance Sheet Information (Q3)

9 Months Ended

Sep. 30, 2023

Supplemental Condensed Balance Sheet Information

7. Supplemental Condensed Balance Sheet Information

Other receivables

Other receivables consisted of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
Rebates receivable	$36,556	$27,955
Other	191	246
Total other receivables	$36,747	$28,201

Inventory

Inventory consisted of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
Intravenous drugs	$27,508	$25,674
Oral pharmaceuticals	10,336	10,802
Total inventories	$37,844	$36,476

Property and Equipment, net

Property and equipment, net consisted of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
Leasehold improvements	$30,078	$26,076
Furniture, fixtures and equipment	2,722	2,669
Medical equipment	12,659	11,003
Computer equipment	3,325	3,115
Signs	147	129
Automobiles	59	69
Software	4,412	4,834
Construction-in-progress	6,150	1,433
Property and equipment, gross	59,552	49,328
Accumulated depreciation and amortization	(23,312)	(17,348)
Property and equipment, net	$36,240	$31,980

Accrued Other

Accrued other consisted of the following at September 30, 2023 and December 31, 2022:

	As of September 30, 2023	As of December 31, 2022
Refund liability	$14,521	$14,544
Deferred social security taxes - COVID	—	378
Excise taxes payable	2,700	—
Current portion of finance lease liabilities	630	425
Other	5,126	2,453
Total accrued other	$22,977	$17,800

Basis of Presentation and Significant Accounting Policies (Q3) (Policies)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Principles of Consolidation

Basis of Presentation

Refer to Note 1 for the accounting treatment of the Business Combination.

Refer to Note 4 for further information on the VIEs. Refer to Note 1 for the accounting treatment of the Reverse Recapitalization.

Accounting Estimates and Assumptions

Segments

Revenue Recognition

The Company monitors revenue and receivables to prepare estimated contractual allowances for the anticipated differences between billed and reimbursed amounts. Payments from third-party payors and Government programs including Medicare and Medicaid may be subject to audit and other retrospective adjustments. Such amounts are considered on an estimated basis when net patient revenue is recorded and are adjusted as final adjustments are determined. For the years ended December 31, 2022, 2021, and 2020, such resulting historic adjustments have been immaterial to the consolidated financial statements.

The Company uses the cost-to-cost measure of progress for the Company’s contract because it best depicts the transfer of control to the customer as the performance obligation is fulfilled. For this method, the Company compares the contract costs incurred to date to the estimated total contract costs through completion. As part of the client proposal and contract negotiation process, the Company develops a detailed project budget for the direct costs and reimbursable costs based on the scope of the work, the complexity of the study, the geographical location involved and the Company’s historical experience. The estimated total contract costs at the project level are reviewed and revised periodically throughout the life of the contract, with adjustments to revenue resulting from such revisions being recorded on a cumulative basis in the period in which the revisions are identified. Contract costs consist primarily of direct labor and other reimbursable project-related costs such as travel, third-party vendor costs and investigator fees. The Company establishes pricing based on the Company’s internal pricing guidelines, discount agreements, if any, and negotiations with the client. The transaction price is the contractually defined amount. For the year ended December 31, 2022, the Company recognized revenue of $4.3 million related to the clinical trial which is included within other revenue.

Short-term Marketable Securities

Investments in marketable securities consist of corporate bonds and U.S. Treasury securities.

Short-term Marketable Securities

Equity Investment in Affiliate

Noncontrolling Interests

The Company consolidates the results of entities in which it has a controlling financial interest. Refer to Note 14 for additional considerations and presentation for noncontrolling interest.

Mezzanine Equity

New AON Series A Preferred Stock is redeemable for cash or the value of the property, rights or securities to be paid or distributed in the event of a Deemed Liquidation Event (which is outside of the Company’s control). As a result, Management has determined that the New AON Series A Preferred Stock should be classified as mezzanine equity. As of September 30, 2023, the Preferred Stock are recorded at their initial carrying value, net of offering costs of $0.8 million. The Series A Preferred Stock are not being accreted to redemption value, as the redemption is not probable. The Series A Preferred Stock are classified outside of members’ equity on the consolidated balance sheets. Refer to Note 14 for mezzanine equity presentation considerations for redeemable noncontrolling interest.

Business Combinations

Offering Costs

Professional Liability

Fair Value of Financial Instruments

Level 1

Inputs to the valuation methodology are quoted prices (unadjusted) for an identical asset or liability in an active market.

Level 2

Level 3

Fair Value of Financial Instruments

Level 1

Inputs to the valuation methodology are quoted prices (unadjusted) for an identical asset or liability in an active market.

Level 2

Level 3

Inputs to the valuation methodology are unobservable and significant to the fair value measurement of the asset or liability.

Warrant Liabilities

long-term liabilities on the condensed consolidated balance sheets. The fair value was estimated at September 30, 2023, using the Black-Scholes Option Pricing model using the following assumptions:

Expected annual dividend yield			0.0%
Expected volatility			0.75%
Risk-free rate of return			4.60%
Expected Option Term			5.0

Earnings Per Share

Recently Adopted Accounting Pronouncements and Recently Issued Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

Related Parties (FY) (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2023

Dec. 31, 2022

Transactions Notes Receivable

	As of September 30, 2023	As of December 31, 2022	Original Principal	Issue Date	Maturity Date
Notes receivable
Note 2	$1,027	$1,057	$5,355	5/1/2019	4/30/2024
Note 3	42	119	491	6/1/2019	5/31/2024
Note 6	—	351	1,111	5/22/2020	5/22/2023
Note 8	2,065	2,221	2,816	5/1/2020	5/1/2025
Note 9	—	125	125	1/24/2022	6/30/2023
Total notes receivables	3,134	3,873
Less: Current portion of notes receivable	$(1,630)	(1,797)
Notes receivable, less current portion	$1,504	$2,076

The notes bear interest at the Company’s incremental borrowing rate (1.57% at December 31, 2022 and 1.55% at December 31, 2021).

	As of December 31,		Original Principal	Issue Date	Maturity Date
	2022	2021	Original Principal	Issue Date	Maturity Date
Notes receivable
Note 2	$1,057	$1,294	$5,355	5/1/2019	4/30/2024
Note 3	119	217	491	6/1/2019	5/31/2024
Note 4	—	259	917	8/1/2019	7/31/2024
Note 6	351	680	1,111	5/22/2020	5/22/2023
Note 8	2,221	2,513	2,816	5/1/2020	5/1/2025
Note 9	125	—	125	1/24/2022	6/30/2023
Total notes receivables	3,873	4,963
Less: Current portion of notes receivable	(1,797)	(1,812)
Notes receivable, less current portion	$2,076	$3,151

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) (FY) - USD ($)

12 Months Ended

Dec. 31, 2022

Dec. 31, 2021

Dec. 31, 2020

Revenue

$ 1,149,670,000

$ 943,747,000

$ 724,743,000

Costs and expenses

^[1],[2]

1,054,217,000

865,788,000

658,638,000

Income (Loss) from operations

89,887,000

77,048,000

44,033,000

Total costs and expenses

1,144,104,000

942,836,000

702,671,000

5,566,000

911,000

22,072,000

Other income (expense)

Interest expense

(3,417,000)

(1,419,000)

(1,116,000)

Interest income

151,000

127,000

32,000

Other income, net

289,000

736,000

180,000

Income before income taxes

2,589,000

355,000

21,168,000

Income tax expense (benefit)

460,000

(783,000)

Net income (loss) before noncontrolling interest

2,589,000

(105,000)

21,951,000

Net income (loss) attributable to Legacy AON Shareholders prior to the reverse recapitalization

2,589,000

(105,000)

21,951,000

Net loss attributable to Class A Common Stockholders

$ 0

Earnings (loss) per Class A Common Stock:

Earnings (loss) per unit, basic (in usd per share)

$ 0

Earnings (loss) per unit, diluted (in usd per share)

$ 0

Other comprehensive loss:

Unrealized losses on marketable securities

$ (117,000)

$ 0

Other comprehensive gain (loss)

(117,000)

Comprehensive income (loss)

2,472,000

(105,000)

21,951,000

Patient Service Revenue, Net [Member]

Revenue

HHS Grant Income [Member]

1,137,932,000

938,242,000

714,678,000

Revenue

6,841,000

Other Revenue [Member]

Revenue