X0306 4 2014-10-21 0001604464 Atara Biotherapeutics, Inc. ATRA 0001465143 DP VIII Associates, L.P. C/O DOMAIN ASSOCIATES, LLC ONE PALMER SQUARE PRINCETON NJ 08542 0 0 1 0 0001024000 BLAIR JAMES C C/O DOMAIN ASSOCIATES, LLC ONE PALMER SQUARE PRINCETON NJ 08542 0 0 1 0 0001207786 DOVEY BRIAN H C/O DOMAIN ASSOCIATES, LLC ONE PALMER SQUARE PRINCETON NJ 08542 0 0 1 0 0001013425 TREU JESSE I C/O DOMAIN ASSOCIATES, LLC ONE PALMER SQUARE PRINCETON NJ 08542 0 0 1 0 0001207789 SCHOEMAKER KATHLEEN K C/O DOMAIN ASSOCIATES, LLC ONE PALMER SQUARE PRINCETON NJ 08542 0 0 1 0 0001196863 VITULLO NICOLE C/O DOMAIN ASSOCIATES, LLC ONE PALMER SQUARE PRINCETON NJ 08542 0 0 1 0 0001354718 Halak Brian K C/O DOMAIN ASSOCIATES, LLC ONE PALMER SQUARE PRINCETON NJ 08542 0 0 1 0 Common Stock 2014-10-21 4 C 0 14049 A 14049 D Common Stock 2014-10-21 4 P 0 1841 11.00 A 15890 D Series A Preferred Stock 2014-10-21 4 C 0 9443 0 D Common Stock 9443 0 D Series B Preferred Stock 2014-10-21 4 C 0 4606 0 D Common Stock 4606 0 D The securities reported as directly beneficially owned by the designated Reporting Person may be deemed to be indirectly beneficially owned by each of the Reporting Owners listed below, each of whom is a managing member of One Palmer Square Associates VIII, LLC, the sole general partner of the designated Reporting Person. Pursuant to Instruction 4(b)(iv) of Form 4, each such individual has elected to report as indirectly beneficially owned the entire number of securities owned by the designated Reporting Person, however each of them disclaims beneficial ownership of any securities, and any proceeds thereof, that exceed his or her pecuniary interest therein and/or that are not actually distributed to him or her. As managing members of the sole general partner of Domain Partners VIII, L.P., each Reporting Owner listed below may also be deemed to indirectly beneficially own the securities of the Issuer held by Domain Partners VIII, L.P., as reported on a Form 4 for Domain Partners VIII, L.P. filed on the same date as this Form 4. All outstanding shares of the Issuer's preferred stock automatically converted into Common Stock upon the closing of the Issuer's initial public offering for no additional consideration. The preferred stock had no expiration date. /s/ Kathleen K. Schoemaker, as Managing Member of One Palmer Square Associates VIII, LLC, the general partner of DP VIII Associates, L.P., individually and as Attorney-in-Fact for J. Blair, B. Dovey, J. Treu, N. Vitullo and B. Halak 2014-10-21