X0508 4 2026-03-01 0001624322 Business First Bancshares, Inc. BFST 0002076134 Roemer Heather G. 500 LAUREL STREET, SUITE 101 BATON ROUGE LA 70801 1 EVP, CAO 0 COMMON STOCK 2026-03-01 4 M 0 1141 A 20733 D COMMON STOCK 2026-03-01 4 D 0 1141 27.30 D 19592 D COMMON STOCK 8817 I By spouse COMMON STOCK 7230 I As custodian for minor children Restricted Stock Units 2026-03-01 4 M 0 1141 D Common Stock 1141 4516 D Restricted Stock Units 0 2026-03-02 4 A 0 722 A Common Stock 722 5238 D Restricted Stock Units 0 2026-03-02 4 A 0 2891 A Common Stock 2891 8129 D Includes: (a) 1,927 shares of restricted stock granted on February 1, 2024, which vest on March 31, 2026; and (b) 725 shares held jointly with spouse. The reporting person received an award of 3,459 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. These shares were acquired upon the partial vesting of the previously reported time-based restricted stock units granted to the reporting person on March 1, 2025. The reporting person has irrevocably elected to defer the reported securities under the b1BANK Deferred Compensation Plan (the "Deferred Compensation Plan"). In accordance with the Deferred Compensation Plan, the reporting person will receive a lump sum cash distribution in an amount equal to the vested securities deferred under the Deferred Compensation Plan, plus any earnings or losses attributable thereto, on the first business day following the month in which the reporting person's separation of service, death, or disability occurs. Reflects the grant of 722 time-based restricted stock units granted to the reporting person on March 2, 2026, of which 240 shares will vest on March 2, 2027, 240 shares will vest on March 2, 2028, and the remaining 242 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. Reflects the grant of 2,891 time-based restricted stock units granted to the reporting person on March 2, 2026, of which 963 shares will vest on March 2, 2027, 963 shares will vest on March 2, 2028, and the remaining 965 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. The reporting person has irrevocably elected to defer the reported securities under the Deferred Compensation Plan. In accordance with the Deferred Compensation Plan, the reporting person will receive a lump sum cash distribution in an amount equal to the vested securities deferred under the Deferred Compensation Plan, plus any earnings or losses attributable thereto, on the first business day following the month in which the reporting person's separation of service, death, or disability occurs. Includes: (a) 2,198 time-based restricted stock units granted to the reporting person on December 12, 2024, which will vest in two substantially equal installments on the second and third anniversary of the issuance date; (b) 2,318 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; (c) 722 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 issuance date; and (d) 2,891 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 issuance date. /s/ Saundra Strong, as attorney-in-fact for Heather G. Roemer 2026-03-03