[Form 4] Affiliated Managers Group Insider Trading Activity

Rhea-AI Filing Summary

Karen L. Alvingham, a director of Affiliated Managers Group, Inc. (AMG), reported changes in her beneficial ownership on 08/14/2025–08/15/2025. The filing shows the vesting of previously awarded equity: 1,092 shares of common stock were issued upon vesting at $0 per share and 84 shares were automatically surrendered to the company to satisfy tax withholding at an indicated price of $218.70 per share. The report also shows 262 deferred stock units credited from elected cash fees, each unit equal to one share and distributable in common stock upon separation from board service. Following the reported transactions, the filing lists beneficial ownership figures of 11,865 shares of common stock and 4,313 shares represented by deferred stock units (inclusive of prior deferred units).

Positive

• Director alignment: Election to defer cash fees into deferred stock units ties director compensation to company equity and aligns interests with shareholders.
• No open-market insider sales reported: Acquisitions reflect vesting and deferrals rather than sales that could signal liquidity-driven exits.

Negative

• Tax-related share surrender: Automatic surrender of 84 vested shares reduces the director's net share increase from the vesting event.

Insights

Corporate Governance Expert

TL;DR: Routine director equity vesting and tax withholding; shows alignment with shareholder interests through deferred compensation.

The Form 4 documents scheduled vesting of previously granted awards and the automatic surrender of a small number of shares to satisfy tax withholding. The filing also confirms the director elects to defer cash fees into stock-linked units, which are distributable as common stock upon separation from board service. These are standard governance-related equity actions and do not indicate unusual insider activity or corrective transactions.

Securities Analyst

TL;DR: Transactions are routine, non-cash-accretion vesting events with limited immediate market impact.

The reported acquisition of 1,092 vested shares at $0 reflects compensation vesting rather than open-market purchases; 84 shares were surrendered to cover taxes at a referenced per-share price, reducing net share count. Deferred stock units (262 added) increase future share delivery exposure but are not currently tradable shares. Overall, the changes are small relative to reported beneficial ownership totals and appear immaterial to the company’s capitalization.

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^*

Alvingham Karen L.

(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		1,092	A	$0(1)	11,949	D
Common Stock	08/15/2025		F		84(2)	D	$218.7	11,865	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	(3)	08/14/2025		A		262		(3)	(3)	Common Stock	262	$0	262	D
Stock Units	(1)	08/15/2025		M			1,092	(1)	(1)	Common Stock	1,092	$0	4,313(4)	D

Explanation of Responses:

1. Reflects the vesting of previously reported awards. Awards vest 2022-2027.

2. Reflects the automatic surrender of shares of common stock to the Company to satisfy tax withholding obligations related to the vesting of the awards described above.

3. 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.

4. 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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

Who filed the Form 4 and what is their role at AMG?

The Form 4 was filed for Karen L. Alvingham, who is reported as a Director of Affiliated Managers Group, Inc. (AMG).

What transactions were reported on the 08/14/2025–08/15/2025 Form 4 for AMG?

The filing reports the vesting of 1,092 common shares, the surrender of 84 shares to satisfy tax withholding, and the credit of 262 deferred stock units from deferred cash fees.

At what price were the vested shares recorded in the Form 4?

The vested shares are reported with a price of $0 (reflecting issuance upon vesting); the surrendered shares reference $218.70 per share related to tax withholding.

How many shares did the reporting person beneficially own after these transactions?

The Form 4 lists 11,865 shares of common stock beneficially owned following the reported transactions and 4,313 shares represented by deferred stock units (inclusive of prior deferred units).

What are deferred stock units in this filing?

Deferred stock units reflect elected deferral of cash fees notionally invested in a measurement fund tracking AMG common stock; each unit equals one share and becomes distributable in common stock upon separation from board service.