Gillan-Myer Maureen A 4

What Happened

• Maureen A. Gillan-Myer, EVP, Chief Administrative & HR Officer of Community Financial System, Inc. (CBU), had a 2023 three‑year performance-based restricted stock award vest on March 4, 2026. She was issued 2,562.063 shares of common stock (2,304 shares from the award plus 258.0628 shares from a dividend reinvestment feature). The award shares were recorded at $0.00 per share.
• To satisfy tax withholding on the vesting, 943.063 shares were disposed (withheld) at a notional price of $59.87 per share, equal to $56,461.

Key Details

• Transaction date: March 4, 2026. Filing date: March 6, 2026 (timely Form 4 filing).
• Awarded/acquired: 2,562.063 shares @ $0.00 (vesting of performance-based restricted stock).
• Withheld/disposed for taxes: 943.063 shares @ $59.87 = $56,461.
• Award breakdown (footnote): 2,304 shares vested from the 2023 performance award; 258.0628 shares came from dividend reinvestment under the 2022 LTIP (F1).
• Tax withholding explanation: payment of tax liability associated with restricted stock vesting (F2).
• Other note: some reported shares relate to the company 401(k) plan per plan statement (F3).
• Shares owned after the transaction: not specified in the provided excerpt.

Context

• This was a vesting/award event (code A) rather than an open‑market purchase or voluntary sale; the withholding of shares to cover taxes (code F) is a routine administrative step and not a market sale intended to signal sentiment.
• The award vested based on achievement of predetermined performance criteria at the target level; the filing does not indicate any additional cashless sale of shares beyond the withholding.