X0306 4 2020-11-13 0 0001604464 Atara Biotherapeutics, Inc. ATRA 0001702457 Newell Joe C/O ATARA BIOTHERAPEUTICS, INC. 611 GATEWAY BLVD., SUITE 900 SOUTH SAN FRANCISCO CA 94080 0 1 0 0 Chief Operations Officer Common Stock 2020-11-13 4 M 0 3500 12.15 A 125703 D Common Stock 2020-11-13 4 S 0 6200 18.36 D 119503 D Common Stock 2020-11-13 4 S 0 1300 19.12 D 118203 D Employee Stock Option (Right to Buy) 12.15 2020-11-13 4 M 0 2833 0.00 D 2030-02-28 Common Stock 2833 50167 D Employee Stock Option (Right to Buy) 12.15 2020-11-13 4 M 0 667 0.00 D 2030-02-28 Common Stock 667 16333 D Transaction pursuant to Rule 10b5-1 Plan adopted September 14, 2020. The price in Column 4 is a weighted average sale price. The prices actually received ranged from $17.84 to $18.74. The reporting person will provide to the issuer, any security holder of the issuer, or the SEC staff, upon request, information regarding the number of shares sold at each price within the range. The price in Column 4 is a weighted average sale price. The prices actually received ranged from $18.85 to $19.18. The reporting person will provide to the issuer, any security holder of the issuer, or the SEC staff, upon request, information regarding the number of shares sold at each price within the range. 1/48th of the shares subject to the stock option vest and become exercisable each month with the initial installment vesting on April 1, 2020, subject to the reporting person's continuous service. /s/ David Tucker, Attorney-in-Fact for Joe Newell 2020-11-16