[Form 4] Affiliated Managers Group Insider Trading Activity

Rhea-AI Filing Summary

Loren M. Starr, a director of Affiliated Managers Group, Inc. (AMG), reported changes in beneficial ownership. On 08/14/2025 and 08/15/2025 the filing shows acquisition events that increased her holdings. A previously granted award vested in 2025 and is reflected as 544 shares reported on 08/15/2025 (listed at $0) and 334 deferred stock units reported on 08/14/2025 arising from cash fees elected for deferral under the company plan. Following the reported transactions, the filing shows 1,285 shares directly owned and 2,680 deferred stock units in total, inclusive of previously reported units.

Positive

• Director increased direct ownership by 544 shares following a reported vesting event
• Deferred compensation converted into 334 deferred stock units, strengthening alignment with shareholders

Negative

• None.

Insights

Corporate Governance Expert

TL;DR: Routine director compensation and vesting increased insider ownership; no unusual trading patterns reported.

The Form 4 documents standard director compensation mechanics: the vesting of a previously reported equity award and director cash fees converted into deferred stock units notionally tied to AMG common stock. Both items are disclosed as acquisitions with zero reported price, consistent with internal award vesting and deferral elections rather than open-market purchases. The filing increases the director's direct and deferred holdings but contains no indications of sales, hedging, or unusual transactions that would raise governance concerns.

Securities Analyst

TL;DR: Changes are minor and administrative, reflecting compensation vesting and fee deferral, with limited market impact.

The reported increments—544 common stock units and 334 deferred stock units—are modest absolute amounts and are described as vesting or fee deferrals. The disclosure includes post-transaction balances (1,285 direct shares and 2,680 deferred units total), clarifying ownership but not suggesting material shifts in control or liquidity. From a securities perspective, these are routine Schedule 16 disclosures intended to keep public records current.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

STARR LOREN M

(Last) (First) (Middle)

C/O AFFILIATED MANAGERS GROUP, INC.

777 SOUTH FLAGLER DRIVE

(Street)

WEST PALM BEACH FL 33401

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
AFFILIATED MANAGERS GROUP, INC. [ AMG ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
08/14/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	08/15/2025		M		544	A	$0(1)	1,285	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Deferred Stock Units	(2)	08/14/2025		A		334		(2)	(2)	Common Stock	334	$0	334	D
Stock Units	(1)	08/15/2025		M			544	(1)	(1)	Common Stock	544	$0	2,680(3)	D

Explanation of Responses:

1. Reflects the vesting of a previously reported award. Award vested in 2025.

2. Reflects cash fees that the director has elected to defer under the Company's deferred compensation plan, which are notionally invested in a measurement fund tracking the Company's common stock during the deferral period. Each deferred stock unit is equal to one share of the Company's common stock, and becomes distributable in common stock upon the reporting person's separation from service as a member of the Board of Directors of the Company.

3. Inclusive of previously reported deferred stock units.

	/s/ Kavita Padiyar, Attorney-in-Fact	08/18/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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FAQ

What transactions did AMG director Loren M. Starr report on Form 4?

The Form 4 reports acquisitions on 08/14/2025 and 08/15/2025: 334 deferred stock units and 544 common stock units (both listed at $0).

Why are some amounts listed with a price of $0 on the Form 4 for AMG (AMG)?

The filing states the $0 amounts reflect the vesting of a previously reported award and the conversion of director fees into deferred stock units, not open-market purchases.

How many AMG shares and deferred units does Loren M. Starr beneficially own after these transactions?

After the reported transactions the Form 4 shows 1,285 direct shares and 2,680 deferred stock units (inclusive of previously reported units).

Do the Form 4 disclosures indicate any sales or hedging by the director at AMG?

No. The Form 4 shows only acquisition-type entries (vesting and deferrals) and does not report any sales or derivative/hedging transactions.

What explains the deferred stock units reported on AMG's Form 4?

The filing explains those units arise from cash fees the director elected to defer under the company’s deferred compensation plan, each unit equaling one share and payable in stock upon separation from board service.