X0206 3 2020-07-09 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 Chief Executive Officer Common Stock 364056 D Common Stock 3972217 I See footnote Common Stock 3645111 I See footnote Common Stock 961445 I See footnote Common Stock 373349 I See footnote Series A Preferred Stock Common Stock 255845 I See footnote Series A-1 Preferred Stock Common Stock 350696 I See footnote Employee Stock Option (Right to Buy) 1.29 2026-02-28 Common Stock 67534 D Employee Stock Option (Right to Buy) 1.173 2026-02-28 Common Stock 114152 D Employee Stock Option (Right to Buy) 13.468 2029-12-11 Common Stock 32076 D Employee Stock Option (Right to Buy) 12.234 2029-12-11 Common Stock 208500 D 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 is a Trustee. The reporting person's minor daughter is the sole beneficiary of the Trust. 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 Twin Prime Investments, an entity wholly owned by the reporting person. Each share of Series A Preferred Stock and Series A-1 Preferred Stock (the "Preferred Stock") is convertible into 0.8019246 shares of Common Stock. The Preferred Stock has no expiration date. The shares are held in the name of Transposagen Biopharmaceuticals, Inc. ("Transposagen"). Dr. Ostertag is a member of the board of directors and majority stockholder of Transposagen. The stock option is fully vested and exercisable. 12.5% of the shares subject to the stock option vested and became exercisable on June 11, 2020, and the remaining shares vest in 42 equal monthly installments thereafter. /s/ Johanna M. Mylet, Attorney-in-Fact 2020-07-09