AFFILIATED MANAGERS GROUP, INC.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)

For the fiscal year ended December 31, 2025

OR

For the transition period from to

Commission File Number 001-13459

(Exact name of registrant as specified in its charter)

777 South Flagler Drive, West Palm Beach, Florida,33401

(Address of principal executive offices)

(800)345-1100

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act:

None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities

Act. Yes ☒ No ☐

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the

Act. Yes ☐No ☒

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the

Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the Registrant was required to

file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be

submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such

shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a

smaller reporting company, or emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,”

“smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition

period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the

Exchange Act. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the

effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C.

7262(b)) by the registered public accounting firm that prepared or issued its audit report.☒

Ifsecurities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements

of the registrant included in the filing reflect the correction of an error to previously issued financial statements.☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of

incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period

pursuant to §240.10D-1(b).☐

Indicate by check mark whether the Registrant is a shell company (as defined in Rule 12b-2 of the Act). Yes☐ No☒

At June 30,2025, the aggregate market value of the common stock held by non-affiliates of the registrant, based upon

the closing price of$196.77 on June 30,2025 on the New York Stock Exchange, was$5,442,489,568. There were 26,684,730

shares of the registrant’s common stock outstanding on February 12, 2026.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s definitive proxy statement to be filed with the Securities and Exchange Commission within

120 days after December 31, 2025, and delivered to stockholders in connection with the registrant’s annual meeting of

stockholders, are incorporated by reference into Part III of this Annual Report on Form 10-K.

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