144 0001485739 XXXXXXXX LIVE 0000723188 COMMUNITY FINANCIAL SYSTEM, INC. 001-13695 5790 Widewaters Parkway, DeWitt New York NY 13214 315-445-2282 John Whipple Director Common APEX CLEARING

350 N. ST. PAUL ST, SUITE 300 DALLAS TX 75201

3937 286456.12 5256 11/25/2024 NYSE Common 11/25/2024 Stock Option Exercise Community Financial System, Inc N 3937 11/25/2024 N/A Y 11/25/2024 /s/ John Whipple