X0306 4 2019-02-06 0 0001604464 Atara Biotherapeutics, Inc. ATRA 0001706400 Porter Derrell C/O ATARA BIOTHERAPEUTICS, INC. 611 GATEWAY BOULEVARD, SUITE 900 SOUTH SAN FRANCISCO CA 94080 0 1 0 0 SVP, Head of Global Commercial Common Stock 2019-02-06 4 F 0 1216 38.47 D 11284 D Common Stock 2019-02-06 4 A 0 12313 0.00 D 23597 D Employee Stock Option (Right to Buy) 38.47 2019-02-06 4 A 0 24625 0.00 A 2029-02-05 Common Stock 24625 24625 D Shares withheld to cover tax obligation from settlement of vested restricted stock units. These restricted stock units vest in four equal annual installments on each of the first, second, third and fourth anniversaries of the grant date, subject to the reporting person's continuous service. 1/48th of the shares subject to the stock option vest and become exercisable each month following February 6, 2019, subject to the reporting person's continuous service. /s/ David Tucker, Attorney-in-Fact for Derrell Porter 2019-02-08