SEI Investments Co

Item 5.02. Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. On December 12, 2025, Alfred P. West, Jr., who founded SEI Investments Company (the "Company") in 1968 and following that served as the Company's chief executive officer for more than 50 years and most recently as Executive Chairman of the Board of Directors (the "Board"), tendered his resignation as a member of the Board and as an officer of the Company and its subsidiaries and affiliates, effective January 1, 2026. Mr. West indicated that his resignation was not because of a disagreement with the Company on any matter relating to the Company's operations, policies or practices. In order to avail the Board as well as the management and employees of the Company the continued benefit of Mr. West's guidance, direction and support in furtherance of the Company's operational and strategic success, the Board appointed Mr. West to serve, effective upon his resignation, as the non-voting Chairman Emeritus of the Board. The Board also appointed current independent member Carl Guarino to serve as the non-executive Chairman of the Board, effective upon Mr. West's resignation, and reduced the size of the Board from nine members to eight, also effective upon Mr. West's resignation. A press release relating to Mr. West's resignation and Mr. Guarino's appointment, issued December 17, 2025, is filed as Exhibit 99.1 to this Current Report on Form 8-K. Item 8.01. Other Events. Also on December 12, 2025, the Board of Directors of SEI Investments Company declared a dividend of $0.52 per share. The cash dividend will be payable to shareholders of record on December 29, 2025 with a payment date of January 12, 2026. Item 9.01. Financial Statements and Exhibits. Exhibit No. Description 99.1 Press Release dated December 17, 2025 of SEI Investments Company

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