X0609 4 2026-09-29 0000350894 SEI INVESTMENTS CO SEIC 0001059374 WEST ALFRED P JR false 1 FREEDOM VALLEY DRIVE OAKS PA 19456 true Chairman Emeritus false Common Stock 2026-09-29 4 S 0 28394 103.403 D 6790057 D Common Stock 2026-09-30 4 S 0 5483 103.162 D 6784574 D Represents the weighted average of a range of sale prices from $103.17 to $103.67. 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 $102.96 to $103.89. 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. /s/ Alfred P. West, Jr., by Lindsay A. Barci, attorney in fact 2026-10-01