X0306 4 2022-02-01 0 0001661460 Poseida Therapeutics, Inc. PSTX 0001765987 Ostertag Eric C/O POSEIDA THERAPEUTICS, INC. 9390 TOWNE CENTRE DRIVE, STE 200 SAN DIEGO CA 92121 1 1 1 0 Executive Chairman Common Stock 2021-12-30 5 G 0 E 93955 0.00 D 603467 D Common Stock 2021-12-30 5 G 0 E 48902 0.00 D 580292 I See footnote Common Stock 2022-02-01 4 A 0 89500 0.00 A 692967 D Common Stock 3659503 I See footnote Common Stock 3358455 I See footnote Common Stock 961445 I See footnote Common Stock 160696 I See footnote Employee Stock Option (Right to Buy) 4.75 2022-02-01 4 A 0 118708 0.00 A 2032-01-31 Common Stock 118708 118708 D Employee Stock Option (Right to Buy) 5.23 2022-02-01 4 A 0 10792 0.00 A 2027-01-31 Common Stock 10792 10792 D The shares are held in the name of Twin Prime Investments, an entity wholly owned by the reporting person. Represents shares issuable upon the vesting of restricted stock units granted pursuant to the Issuer's Equity Incentive Plan. The RSUs are scheduled to vest in two equal annual installments. The shares are held in the name of the Eric Ostertag Living Trust dated March 30, 2016, of which the reporting person is the sole trustee. The shares are held in the name of Titan, LLC, which is owned by the Ostertag Descendents' Trust, of which the reporting person's minor daughter is the sole beneficiary. The reporting person disclaims beneficial ownership of these securities, and this report shall not be deemed an admission that the reporting person is the beneficial owner of the securities for purposes of Section 16 or for any other purpose. The shares are held in the name of the Ostertag Family Trust dated March 30, 2016, of which the reporting person is a trustee. The shares are held in the name of Transposagen Biopharmaceuticals, Inc., of which Dr. Ostertag is a majority stockholder. 25% of the shares subject to the stock option will vest and become exercisable on the six-month anniversary of the grant date listed in column 3 above, and the remaining shares will vest in 18 equal monthly installments thereafter. The exercise price of the incentive stock option is equal to 110% of the fair market value of the Issuer's common stock on the date of grant, due to the reporting person's status as the beneficial owner of 10% or more of the Issuer's common stock on the grant date. /s/ Harry J. Leonhardt, Attorney-in-Fact 2022-02-01