Company: MGRE
Filing Date: 2025-02-28
Form Type: S-3ASR
Source: 0001193125-25-042543
Chunk: 19

Company: AFFILIATED MANAGERS GROUP, INC.
Filing Date: 2025-02-28
Form: S-3ASR
Chunk 19
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 13(a) or Section 15(d) of the Exchange Act (and, where applicable, each filing of an employee benefit plan’s annual report pursuant to Section 15(d) of the Exchange Act) that is
incorporated by reference in this registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide
offering thereof.

Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers and
controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the SEC such indemnification is against public policy as expressed in such Act and is, therefore,
unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer, or controlling person of the registrant in the successful defense of
any action, suit, or proceeding) is asserted by such director, officer, or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in such Act and will be governed by the final adjudication of such issue.

The undersigned registrant hereby undertakes to file an application for the purpose of determining the eligibility of the trustee to act under
subsection (a) of Section 310 of the Trust Indenture Act in accordance with the rules and regulations prescribed by the SEC under Section 305(b)(2) of the Trust Indenture Act.

II-6

SIGNATURES Pursuant to the requirements of the Securities Act of 1933, as amended, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in West Palm Beach, Florida, on this 28 thday of February, 2025.

| AFFILIATED MANAGERS GROUP, INC. |     |                     |
| By:                             |     | /s/ Dava E. Ritchea |
| Name: Dava E. Ritchea           |     |                     |
| Title: