X0609 4 2026-07-28 0000350894 SEI INVESTMENTS CO SEIC 0001972425 Warner Mark Andrew false 1 FREEDOM VALLEY DRIVE OAKS PA 19456 true See Remarks* false Common Stock 2026-07-28 4 M 0 2500 64.43 A 3421 D Common Stock 2026-07-28 4 M 0 2500 64.43 A 5921 D Common Stock 2026-07-28 4 M 0 5000 56.54 A 10921 D Common Stock 2026-07-28 4 M 0 5000 56.54 A 15921 D Common Stock 2026-07-28 4 S 0 2300 101.105 D 13621 D Common Stock 2026-07-28 4 S 0 5300 102.011 D 8321 D Common Stock 2026-07-28 4 S 0 7400 102.972 D 921 D Option to Purchase Common Stock 64.43 2026-07-28 4 M 0 2500 D 2021-12-31 2029-12-09 Common Stock 2500 0 D Option to Purchase Common Stock 64.43 2026-07-28 4 M 0 2500 D 2025-12-31 2029-12-09 Common Stock 2500 0 D Option to Purchase Common Stock 56.54 2026-07-28 4 M 0 5000 D 2022-12-31 2030-12-08 Common Stock 5000 0 D Option to Purchase Common Stock 56.54 2026-07-28 4 M 0 5000 D 2024-12-31 2030-12-08 Common Stock 5000 0 D Represents the weighted average of a range of sale prices from $100.45 to $101.37. The reporting person undertakes to provide to the Staff of the Securities and Exchange Commission, the Company, or any stockholder of the Company, upon request, full information regarding the number of shares sold at each separate price. Represents the weighted average of a range of sale prices from $101.57 to $102.41. The reporting person undertakes to provide to the Staff of the Securities and Exchange Commission, the Company, or any stockholder of the Company, upon request, full information regarding the number of shares sold at each separate price. Represents the weighted average of a range of sale prices from $102.60 to $103.23. The reporting person undertakes to provide to the Staff of the Securities and Exchange Commission, the Company, or any stockholder of the Company, upon request, full information regarding the number of shares sold at each separate price. Received as employment compensation. Title: Chief Accounting Officer and Controller /s/ Mark Andrew Warner by Lindsay A. Barci, attorney in fact 2026-07-30