Exhibit 99.A
Joint Filing Agreement
The undersigned hereby agree that the statement on Schedule 13G with respect to the Common Stock, par value $0.0001 of Atara Biotherapeutics, Inc., dated as of February 14, 2020, is, and any amendments thereto (including amendments on Schedule 13D) signed by each of the undersigned shall be, filed on behalf of each of us pursuant to and in accordance with the provisions of Rule 13d-1(k) under the Securities Exchange Act of 1934.
| Date: February 14, 2020 | MAVERICK CAPITAL, LTD. | |||
| By: | Maverick Capital Management, LLC, | |||
| Its General Partner | ||||
| By: Lee S. Ainslie III, Manager | ||||
| By: | /s/ Mark Gurevich | |||
| Mark Gurevich Under Power of Attorney dated March 15, 2018 | ||||
| MAVERICK CAPITAL MANAGEMENT, LLC | |||
| By: | Lee S. Ainslie III, Manager | ||
| By: | /s/ Mark Gurevich | ||
|
Mark Gurevich Under Power of Attorney dated March 15, 2018 | ||
| LEE S. AINSLIE III | |||
| By: | /s/ Mark Gurevich | ||
|
Mark Gurevich March 15, 2018 | |||
| ANDREW H. WARFORD | ||
| By: | /s/ Mark Gurevich | |
|
Mark Gurevich March 16, 2018 | ||