X0508 4 2026-03-01 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 2026-03-01 4 M 0 1337 A 15200 D COMMON STOCK 2026-03-01 4 F 0 366 27.30 D 14834 D Restricted Stock Units 2026-03-01 4 M 0 1337 D Common Stock 1337 5299 D Restricted Stock Units 0 2026-03-02 4 A 0 4020 A Common Stock 4020 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 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. The reporting person received an award of 4,052 time-based restricted stock units on March 1, 2025, vesting in three substantially equal installments on the first, second, and third anniversary of the issuance date. Reflects the grant of 4,020 time-based restricted stock units granted to the reporting person on March 2, 2026, of which 1,340 shares will vest on March 2, 2027, 1,340 shares will vest on March 2, 2028, and the remaining 1,340 shares will vest on March 2, 2029. Each time-based restricted stock unit is economically equivalent to one share 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 2026-03-03