X0508 4 2025-03-18 0000723188 COMMUNITY FINANCIAL SYSTEM, INC. CBU 0001486057 Parente John C/O COMMUNITY FINANCIAL SYSTEM, INC. 5790 WIDEWATERS PARKWAY DEWITT NY 13214 1 0 Common Stock 2025-03-19 4 M 0 1430 0 A 69816.3212 D Phantom Stock (Deferred Stock Units) 0 2025-03-18 4 A 0 1225 0 A Common Stock 1225 2655.373 D Phantom Stock (Deferred Stock Units) 0 2025-03-19 4 M 0 1430 0 D Common Stock 1430 1225 D On March 19, 2025, the reporting person's phantom stock units were settled for 1,430 shares of Community Financial System, Inc. common stock, and .373 shares were settled in cash at the price of $58.10 per share. The reporting person has received deferred stock units under the Community Financial System, Inc. 2022 Long-Term Incentive Plan, as amended (the "Plan"). Each phantom stock unit which represents a deferred stock unit is the economic equivalent of one share of Community Financial System, Inc. common stock and will be settled in common stock at a predetermined date. Includes 13.032, 11.2154, and 11.1256 units of phantom stock acquired as dividend equivalents on July 10, 2024, October 10, 2024, and January 10, 2025, respectively, under the Plan. /s/ Danielle M. Cima, pursuant to a Confirming Statement executed by John Parente 2025-03-20