X0306 4 2020-12-15 0 0001826892 BioAtla, Inc. BCAB 0001835116 Sievers Eric C/O BIOATLA, INC. 11085 TORREYANA ROAD SAN DIEGO CA 92121 0 1 0 0 Chief Medical Officer Employee Stock Option (right to buy) 18.00 2020-12-15 4 A 0 77471 0.00 A 2030-12-15 Common Stock 77471 77471 D The option vests over a period of four years, with 25% of the shares underlying the option vesting on December 15, 2021, the first anniversary of the date of grant, and the remainder vesting in 36 substantially equal monthly installments thereafter, subject to the reporting person's continued employment through the applicable vesting dates. /s/ Eric Sievers 2020-12-17