X0508 4 2025-08-06 0000836147 MIDDLEFIELD BANC CORP MBCN 0002008413 Winters Sarah A 15985 EAST HIGH STREET MIDDLEFIELD OH 44062 1 EVP/CHRO 0 Common Stock 2025-08-06 4 A 0 853 27.11 A 853 D Common Stock 2025-08-06 4 F 0 248 27.11 D 605 D Conditional Stock Award 2028-01-14 Common Stock 2828 2828 D Conditional Stock Award 2027-09-06 Common Stock 1708 1708 D The acquisition represents the vesting of restricted stock granted to the reporting person on August 6, 2024. The shares vested on the first anniversary of the grant date. The award represents a grant of restricted stock which vests ratably over a three-year period provided that Mrs. Winters remains continuously employed by Middlefield as of each vesting date. Until the award vests, the award confers no right to vote, no right to dividends, and no other shareholder rights to the recipient. The details of the vesting conditions may be found in a Form 8-K filing dated January 17, 2025. Each restricted stock unit represents the right to receive, at settlement, one share of common stock. The award represents a grant of restricted stock which vests ratably over a three-year period provided that Mrs. Winters remains continuously employed by Middlefield as of each vesting date. Until the award vests, the award confers no right to vote, no right to dividends, and no other shareholder rights to the recipient. The details of the vesting conditions may be found in a Form 8-K filing dated September 4, 2024. /s/ Sarah A. Winters by Julie E. Shaw Power of Attorney 2025-08-07