X0508 4 2023-08-16 0 0000036029 FIRST FINANCIAL BANKSHARES INC FFIN 0001554713 Butler Ronald David II P. O. BOX 701 ABILENE TX 79510 0 1 0 0 CAO 0 Common Stock 2023-08-16 4 F 0 139 29.53 D 146627 D Common Stock 2023-08-16 4 A 0 4063 0.00 A 150690 D Common Stock 2023-08-16 4 D 0 565 D 150125 D Employee Stock Option, Right to Buy 29.53 2023-08-16 4 A 0 14289 0.00 A 2033-08-16 Common Stock 14289 14289 D Deferred Stock Units 2023-08-16 4 A 0 565 A Common Stock 565 565 D The reporting person elected, in accordance with the Registrant's 2021 Omnibus Stock and Incentive Plan, to exercise his right to have the Registrant withhold 139 shares of the Registrant's common stock to pay income taxes related to vesting of previously granted restricted stock units. Reflects grant of restricted stock units (RSUs) which vest in three approximately equal installments on each of the three anniversaries of the grant date. In connection with the vesting on August 16, 2023, of 565 restricted stock units previously granted to Mr. Butler on August 16, 2022, Mr. Butler's receipt of 565 shares of common stock was deferred resulting in Mr. Butler's receipt instead of 565 shares of deferred stock units into the First Financial Bankshares, Inc. Supplemental Executive Retirement Plan, as amended and restated effective July 26, 2022 (the "SERP"). Mr. Butler is therefore reporting the disposition of 565 restricted stock units in exchange for an equal number of shares of deferred stock units under the SERP, which are payable upon Mr. Butler's termination of employment. The options vest 33.33% after one year from the grant date, 66.66% after the second year, and 100% after the third year. By: Michelle S. Hickox Attorney in Fact for Ronald D. Butler, II 2023-08-18