X0306 4 2021-11-30 0 0001826892 BioAtla, Inc. BCAB 0001205375 SHORT JAY M PHD C/O BIOATLA, INC. 11085 TORREYANA ROAD SAN DIEGO CA 92121 1 1 1 0 Chief Executive Officer Common Stock 2021-11-30 2021-12-03 4 S 0 7519 23.997 D 1360914 D Common Stock 2021-11-30 2021-12-03 4 S 0 8126 24.676 D 1352788 D Common Stock 2021-11-30 2021-12-03 4 S 0 2845 25.379 D 1349943 D Common Stock 2021-12-01 2021-12-06 4 S 0 7829 22.186 D 1342114 D Common Stock 2021-12-01 2021-12-06 4 S 0 13539 23.266 D 1328575 D Common Stock 2021-12-01 2021-12-06 4 S 0 2953 24.224 D 1325622 D Common Stock 2021-12-02 2021-12-06 4 S 0 4715 21.741 D 1320907 D Common Stock 2021-12-02 2021-12-06 4 S 0 96 22.471 D 1320811 D Common Stock 793547 I By Spouse Common Stock 258727 I By Carolyn Short 2020 Irrevocable Gift Trust Common Stock 258727 I By Jay Short 2020 Irrevocable Gift Trust Common Stock 302324 I By Capia IP, LLC Represents shares of the Issuer's common stock sold by the reporting person to cover taxes due upon the release and settlement of the vested RSUs. The range of prices for the shares of Common Stock is from $23.33 to $24.32. The reporting person undertakes that he will provide, upon request by the staff of the U.S. Securities and Exchange Commission, full information regarding the number of securities sold at each separate price. The range of prices for the shares of Common Stock is from $24.33 to $25.25. The reporting person undertakes that he will provide, upon request by the staff of the U.S. Securities and Exchange Commission, full information regarding the number of securities sold at each separate price. The range of prices for the shares of Common Stock is from $25.30 to $25.38. The reporting person undertakes that he will provide, upon request by the staff of the U.S. Securities and Exchange Commission, full information regarding the number of securities sold at each separate price. The range of prices for the shares of Common Stock is from $21.79 to $22.73. The reporting person undertakes that he will provide, upon request by the staff of the U.S. Securities and Exchange Commission, full information regarding the number of securities sold at each separate price. The range of prices for the shares of Common Stock is from $22.79 to $23.77. The reporting person undertakes that he will provide, upon request by the staff of the U.S. Securities and Exchange Commission, full information regarding the number of securities sold at each separate price. The range of prices for the shares of Common Stock is from $23.80 to $24.68. The reporting person undertakes that he will provide, upon request by the staff of the U.S. Securities and Exchange Commission, full information regarding the number of securities sold at each separate price. The range of prices for the shares of Common Stock is from $21.40 to $22.37. The reporting person undertakes that he will provide, upon request by the staff of the U.S. Securities and Exchange Commission, full information regarding the number of securities sold at each separate price. The range of prices for the shares of Common Stock is from $22.40 to $22.51. The reporting person undertakes that he will provide, upon request by the staff of the U.S. Securities and Exchange Commission, full information regarding the number of securities sold at each separate price. /s/ Christian Vasquez, as Attorney-in-Fact for Jay M. Short 2021-12-07