X0306 4 2020-02-14 0 0001728117 Gossamer Bio, Inc. GOSS 0001553335 Dupont Jakob 3013 SCIENCE PARK ROAD SAN DIEGO CA 92121 0 1 0 0 Chief Medical Officer Common Stock 2020-02-14 4 A 0 46500 0.00 A 46500 D Stock Option (right to buy) 14.55 2020-02-14 4 A 0 71500 0.00 A 2030-02-14 Common Stock 71500 71500 D Represents restricted stock unit award, which will vest in three equal annual installments in accordance with the terms of the award and subject to the Reporting Person's continuous service to the Issuer on each vesting date. 25% of the total number of shares subject to the option will vest on February 14, 2021 and 1/48th of the total number of shares subject to the option vest on the last day of each one-month period thereafter, subject to the Reporting Person's continuous service to the Issuer on each such vesting date. /s/ Jeff Boerneke, Attorney-in-Fact 2020-02-19