X0306 4/A 2018-06-14 2018-06-18 0 0001604464 Atara Biotherapeutics, Inc. ATRA 0001216955 MARCUS JOEL S C/O ALEXANDRIA REAL ESTATE EQUITIES, INC 385 EAST COLORADO BOULEVARD, SUITE 299 PASADENA CA 91101 1 0 0 0 Common Stock 2018-06-14 4 A 0 1500 0.00 A 8500 D Common Stock 4000 I Held by the Joel S. Marcus and Barbara A. Marcus Family Trust Common Stock 908355 I See footnote Non-Qualified Stock Option (Right to Buy) 45.65 2018-06-14 4 A 0 5000 0.00 A 2025-06-13 Common Stock 5000 5000 D These restricted stock units shall vest on June 14, 2019, subject to the Reporting Person's continuous service. Consists of shares of common stock held by Alexandria Equities, LLC. Mr. Marcus is the Chairman, CEO and Founder of Alexandria Real Estate Equities, Inc., which is the managing member of Alexandria Equities, LLC, which has full voting and investment power with respect to the shares owned by Alexandria Equities, LLC. As an officer of Alexandria Real Estate Equities, Inc., Mr. Marcus may be deemed to have voting and investment power with respect to the shares owned by Alexandria Equities, LLC. Mr. Marcus disclaims beneficial ownership of the shares held by Alexandria Equities, LLC, except to the extent of his underlying pecuniary interest therein. The option shall vest on June 14, 2019, subject to the Reporting Person's continuous service. This amendment is being filed solely to attach the Power of Attorney that was inadvertently omitted at the time of filing. /s/ David Tucker, Attorney-in-Fact 2019-03-01