X0306 4 2019-03-31 0001624322 Business First Bancshares, Inc. BFST 0001734796 MCLINDON ANDREW D. 500 LAUREL STREET, SUITE 101 BATON ROUGE LA 70801 1 COMMON STOCK 2019-03-31 4 A 0 296 25.33 A 25840 D COMMON STOCK 2019-04-15 4 P 0 100 24.89 A 25940 D COMMON STOCK 2019-04-22 4 P 0 100 24.47 A 26040 D COMMON STOCK 2019-04-29 4 P 0 100 25 A 26140 D COMMON STOCK 2019-05-06 4 P 0 100 25.43 A 26240 D COMMON STOCK 2019-05-13 4 P 0 100 24.87 A 26340 D COMMON STOCK 2019-05-20 4 P 0 100 25.30 A 26440 D COMMON STOCK 2019-05-28 4 P 0 100 24.96 A 26540 D COMMON STOCK 2019-06-03 4 P 0 100 24.92 A 26640 D COMMON STOCK 2019-06-10 4 P 0 100 25.25 A 26740 D COMMON STOCK 2019-06-17 4 P 0 100 25.20 A 26840 D COMMON STOCK 2019-06-24 4 P 0 100 25.48 A 26940 D COMMON STOCK 2019-07-01 4 P 0 100 25.83 A 27040 D COMMON STOCK 2019-07-08 4 P 0 100 25.80 A 27140 D COMMON STOCK 2019-07-15 4 P 0 100 25.18 A 27240 D COMMON STOCK 2019-07-29 4 P 0 100 25.14 A 27340 D COMMON STOCK 2019-08-05 4 P 0 100 22.65 A 27440 D COMMON STOCK 2019-08-12 4 P 0 100 23.19 A 27540 D COMMON STOCK 2019-08-19 4 P 0 100 24.41 A 27640 D COMMON STOCK 2019-09-04 4 P 0 100 23.45 A 27740 D This transaction was executed in multiple trades at prices ranging from $24.88 to $24.89. The price reported above reflect the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. This transaction was executed in multiple trades at prices ranging from $24.60 to $24.97. The price reported above reflect the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. This transaction was executed in multiple trades at prices ranging from $25.19 to $25.20. The price reported above reflect the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. This transaction was executed in multiple trades at prices ranging from $25.81 to $25.84. The price reported above reflect the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. This transaction was executed in multiple trades at prices ranging from $25.17 to $25.21. The price reported above reflect the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. This transaction was executed in multiple trades at prices ranging from $22.65 to $22.66. The price reported above reflect the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. This transaction was executed in multiple trades at prices ranging from $23.14 to $23.20. The price reported above reflect the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. This transaction was executed in multiple trades at prices ranging from $24.39 to $24.56. The price reported above reflect the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. /s/ Heather Roemer, as attorney-in-fact 2019-09-11