X0609 4 2026-06-25 0001624322 Business First Bancshares, Inc. BFST 0001852200 Ducrest John P. false 500 LAUREL STREET, SUITE 101 BATON ROUGE LA 70801 1 0 COMMON STOCK 2026-06-26 4 M 0 1016 A 14731.772 D COMMON STOCK 2026-06-26 4 D 0 1016 D 13715.772 D COMMON STOCK 6036 I By spouse Restricted Stock Units 0 2026-06-25 4 A 0 998 A Common Stock 998 2014 D Restricted Stock Units 0 2026-06-26 4 M 0 1016 D Common Stock 1016 998 D Reflects the grant of time-based restricted stock units to the reporting person under the Business First Bancshares, Inc. 2024 Equity Incentive Plan on June 25, 2026. The time-based restricted stock units will fully vest on June 25, 2027. Each time-based restricted stock unit is economically equivalent to one share of common stock of the issuer. Under the terms of the relevant restricted stock unit grant, the reported unvested restricted stock units are subject to forfeiture upon the occurrence of certain events. 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. The reporting person received an award of 1,016 time-based restricted stock units on June 26, 2025, vesting on the first anniversary of the issuance date. These shares were acquired upon the vesting of the time-based restricted stock units granted to the reporting person on June 26, 2025. 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. /s/ Heather Roemer, as attorney-in-fact for John P. Ducrest 2026-06-29