X0306 4 2016-03-31 0 0001604464 Atara Biotherapeutics, Inc. ATRA 0001612096 Ciechanover Isaac E. 611 GATEWAY BOULEVARD SUITE 900 SOUTH SAN FRANCISCO CA 94080 1 1 0 0 Chief Executive Officer Common Stock 2016-03-31 4 S 0 300 20.01 D 378911 I See footnote Common Stock 2016-04-01 4 S 0 890 20.04 D 378021 I See footnote Common Stock 450824 I See footnote Common Stock 180000 I See footnote Common Stock 217321 D Transaction pursuant to Rule 10b5-1 Plan adopted December 12, 2014. The price in Column 4 is a weighted average sale price. The prices actually received ranged from $20.00 to $20.01. 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. Shares are held by the Isaac E. Ciechanover and Allison M. Ciechanover Family Trust dated 8/8/08, of which the Reporting Person is a trustee. The price in Column 4 is a weighted average sale price. The prices actually received ranged from $20.00 to $20.12. 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. Sheld are held by the Ciechanover Family GRAT, of which the Reporting Person is a trustee. Sheld are held by the The Ciechanover 2015 GRAT, of which the Reporting Person is a trustee. /s/ Tina Gullotta, Attorney-in-Fact for Isaac E. Ciechanover 2016-04-04