X0609 4 2026-03-31 0001624322 Business First Bancshares, Inc. BFST 0002021584 Carter Donald Chad false 500 LAUREL STREET, SUITE 101 BATON ROUGE LA 70801 1 EVP, Correspondent Banking 0 COMMON STOCK 2026-03-31 4 F 0 317 27.04 D 14517 D Restricted Stock Units 0.0000 Common Stock 9319 9319 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: (a) 2,584 time-based restricted stock units granted on December 12, 2024, which will vest in two substantially equal installments on the second and third anniversary of the issuance date; (b) 2,715 time-based restricted stock units granted to the reporting person on March 1, 2025, which will vest in two substantially equal installments on the second and third anniversary of the issuance date; and (c) 4,020 time-based restricted stock units granted to the reporting person on March 2, 2026, which will vest in three substantially equal installments on the first, second, and third anniversary of the issue date. /s/ Heather Roemer, as attorney-in-fact for Donald Chad Carter 2026-04-02