X0508 4 2025-03-31 0001624322 Business First Bancshares, Inc. BFST 0002021584 Carter Donald Chad 500 LAUREL STREET, SUITE 101 BATON ROUGE LA 70801 1 EVP, Correspondent Banking 0 COMMON STOCK 2025-03-31 4 F 0 506 24.35 D 16717 D Restricted Stock Units Common Stock 0 7908 D Includes units of the employer stock fund through the issuer's 401(k) plan equivalent to 6,799 shares of common stock of the issuer. Includes 1,156 shares of unvested restricted stock granted on February 1, 2024, which will vest on March 31, 2026. Under the terms of the relevant restricted stock grants, the reported shares of unvested restricted stock are subject to forfeiture upon the occurrence of certain events. Includes: (a) 3,856 time-based restricted stock units granted on December 12, 2024, of which 1,272 shares will vest on December 12, 2025, 1,272 shares will vest on December 12, 2026, and the remaining 1,312 shares will vest on December 12, 2027; and (b) 4,052 time-based restricted stock units granted to the Reporting Person on March 1, 2025, of which 1,337 shares will vest on March 1, 2026, 1,337 shares will vest on March 1, 2027, and the remaining 1,378 shares will vest on March 1, 2028. /s/ Heather Roemer, as attorney-in-fact for Donald Chad Carter 2025-04-02