SCHEDULE 13G/A 0001562855 XXXXXXXX LIVE 3 Common Stock 12/31/2025 0001004434 Affiliated Managers Group, Inc. 008252108 777 South Flagler Drive West Palm Beach FL 33401 Rule 13d-1(b) Clarkston Capital Partners, LLC b MI 452500.00 394049.00 452500.00 451619.00 904119.00 N 3.21 IA Clarkston Companies, Inc. b MI 452500.00 394049.00 452500.00 451619.00 904119.00 N 3.21 HC CO Modell Capital LLC b MI 452500.00 394049.00 452500.00 451619.00 904119.00 N 3.21 HC OO Jeffrey A. Hakala b X1 452500.00 394049.00 452500.00 451619.00 904119.00 N 3.21 HC IN Gerald W. Hakala b X1 452500.00 394049.00 452500.00 451619.00 904119.00 N 3.21 HC IN Jeremy J. Modell b X1 452500.00 394049.00 452500.00 451619.00 904119.00 N 3.21 HC IN Affiliated Managers Group, Inc. 777 South Flagler Drive, West Palm Beach, FL 33401 This Schedule 13G/A is filed jointly pursuant to that certain Joint Filing Agreement filed herewith as Exhibit 99.1 by: (1) Clarkston Capital Partners, LLC ("CCP") (2) Clarkston Companies, Inc. ("CC") (3) Modell Capital LLC ("MC") (4) Jeffrey A. Hakala (5) Gerald W. Hakala (6) Jeremy J. Modell 303 E Third St., Suite 110, Rochester, MI 48307 CCP and MC are Michigan limited liability companies. CC is a Michigan corporation. Jeffrey A. Hakala, Gerald W. Hakala, and Jeremy J. Modell (the "Individual Reporting Persons") are citizens of the United States of America. N IA HC CCP is an investment adviser. Collectively, the securities reported in this Schedule 13G/A are held in the accounts of CCP's discretionary clients or in an account over which a control person of CCP has beneficial ownership. The sole members of CCP are CC and MC. The sole owners of CC are Jeffrey A. Hakala and Gerald W. Hakala. The sole member of MC is the Jeremy J. Modell Revocable Living Trust. The information required by Item 4(a) is set forth in Row 9 of the cover page for each of the Reporting Persons and is incorporated herein by reference. Based upon 28,128,908 shares of Common Stock, par value $0.01 per share ("Common Stock"), of Affiliated Managers Group, Inc. (the "Issuer") outstanding as of November 4, 2025, as reported in the Issuer's quarterly report on Form 10-Q filed with the Securities and Exchange Commission on November 6, 2025. 3.21% 452,500 394,049 452,500 451,619 N Y N The shares reported in this statement have been purchased by CCP on behalf of CCP's discretionary clients or by a control person of CCP in an account over which such control person has beneficial ownership. CCP's clients have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of such securities held in their accounts, subject to CCP's general authority to invest and reinvest the assets in each account under its management. N With respect to CC, MC and the Individual Reporting Persons, see Item 4. Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11. Joint Filing Agreement Clarkston Capital Partners, LLC /s/ Jeffrey A. Hakala 02/13/2026 Clarkston Companies, Inc. /s/ Jeffrey A. Hakala 02/13/2026 Modell Capital LLC /s/ Jeremy J. Modell 02/13/2026 Jeffrey A. Hakala /s/ Jeffrey A. Hakala 02/13/2026 Gerald W. Hakala /s/ Gerald W. Hakala 02/13/2026 Jeremy J. Modell /s/ Jeremy J. Modell 02/13/2026