#1 Represents shares of common stock issued upon the vesting of outstanding performance stock units that were subject to performance criteria other than the issuer's stock price.

#2 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 237 shares of the Registrant's common stock to pay income taxes related to vesting of previously granted performance stock units.

#1 Represents shares of common stock issued upon the vesting of outstanding performance stock units that were subject to performance criteria other than the issuer's stock price.

#2 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 237 shares of the Registrant's common stock to pay income taxes related to vesting of previously granted performance stock units.

#1 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 65 shares of the Registrant's common stock to pay income taxes related to vesting of previously granted restricted stock units.

#2 In connection with the vesting on August 16, 2024, of 840 restricted stock units previously granted to Mr. Roewe, Mr. Roewe's receipt of 840 shares of common stock was deferred resulting in Mr. Roewe's receipt instead of 840 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. Roewe is therefore reporting the disposition of 840 restricted stock units in exchange for an equal number of shares of deferred stock units under the SERP, which are payable upon Mr. Roewe's termination of employment.

#1 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 65 shares of the Registrant's common stock to pay income taxes related to vesting of previously granted restricted stock units.

#2 In connection with the vesting on August 16, 2024, of 840 restricted stock units previously granted to Mr. Roewe, Mr. Roewe's receipt of 840 shares of common stock was deferred resulting in Mr. Roewe's receipt instead of 840 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. Roewe is therefore reporting the disposition of 840 restricted stock units in exchange for an equal number of shares of deferred stock units under the SERP, which are payable upon Mr. Roewe's termination of employment.