X0508 4 2025-03-17 0000723188 COMMUNITY FINANCIAL SYSTEM, INC. CBU 0001201821 STICKELS ERIC C/O COMMUNITY FINANCIAL SYSTEM, INC. 5790 WIDEWATERS PARKWAY DEWITT NY 13214 1 0 Common Stock 2025-03-17 4 M 0 451 0 A 35339 D Common Stock 14907.6568 I By Wife's Community Financial System, Inc. 401(k) Phantom Stock (Deferred Stock Units) 2025-03-17 4 M 0 451 0 D Common Stock 451 2913.7399 D On March 17, 2025, the reporting person's phantom stock units were settled for 451 shares of Community Financial System, Inc. common stock, and .3719 shares were settled in cash at the price of $57.23 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 102.5299 units of phantom stock acquired as dividend equivalents under the Plan. Danielle M. Cima, pursuant to a Confirming Statement executed by Eric E. Stickels 2025-03-18