X0508 4 2026-02-23 0000836147 MIDDLEFIELD BANC CORP MBCN 0001286842 MCCASKEY JAMES J 15985 EAST HIGH STREET MIDDLEFIELD OH 44062 1 0 Common Stock 2026-02-23 4 A 0 405 35.18 A 5928.79 D Common Stock 4706.314 D Common Stock 1372 I held by spouse in retirement account Includes shares acquired under MBCN Dividend Reinvestment Plan Includes shares held jointly with spouse. The shares represent accelerated vesting of restricted stock units (RSUs) granted on June 27, 2025. On February 23, 2026, the Compensation Committee of Middlefield's Board of Directors approved the full vesting of all outstanding plan share awards, including the RSUs. For further information regarding the acceleration of the RSUs, please see the Form 8-K Current Report filed by Middlefield with the SEC on February 25, 2026. /s/ James J. McCaskey by Julie E. Shaw Power of Attorney 2026-02-25