X0508 4 2025-12-17 0000836147 MIDDLEFIELD BANC CORP MBCN 0002008413 Winters Sarah A 15985 EAST HIGH STREET MIDDLEFIELD OH 44062 1 EVP/CHRO 0 Common Stock 2025-12-17 4 A 0 5204 37 A 5809 D Common Stock 2025-12-17 4 F 0 1517 37 D 4292 D Conditional Stock Award 2027-09-06 Common Stock 1708 1708 D Conditional Stock Award 2028-01-14 Common Stock 2828 2828 D Amendment of performance share unit award agreement resulting in acceleration of performance share unit grants. The performance share unit award was originally granted on August 6, 2024, and provides for vesting in any earned performance share units upon the payment date, defined as within sixty days after December 31, 2026. 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 2025-12-18