AnhCo Nguyen - 09 Mar 2026 Form 4 Insider Report for Atara Biotherapeutics, Inc. (ATRA)

Role: President and CEO, Director
Signature: /s/ John Chao, Attorney-in-Fact for AnhCo Nguyen
Issuer symbol: ATRA
Transactions as of: 09 Mar 2026
Net transactions value: $0
Form type: 4
Filing time: 11 Mar 2026, 17:46:05 UTC
Previous filing: 04 Mar 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Nguyen AnhCo	President and CEO, Director	C/O ATARA BIOTHERAPEUTICS, INC., 1280 RANCHO CONEJO BOULEVARD, THOUSAND OAKS	/s/ John Chao, Attorney-in-Fact for AnhCo Nguyen	11 Mar 2026	0001977970

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	ATRA	Common Stock	Award		+81,100	+131%	$0.000000^*	143,078	09 Mar 2026	Direct	F1

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	These restricted stock units ("RSUs") vest as to 1/8th of the total number of shares (rounded down to the next whole number of shares) on the second Quarterly Vesting Date (as defined below) following March 9, 2026, and as to 1/8th of the total number of shares (rounded down to the next whole number of shares) on the next seven Quarterly Vesting Dates, such that all of the shares subject to the RSUs shall be vested on the last Quarterly Vesting Date, subject to the reporting person's continuous employment. "Quarterly Vesting Date" means March 1, May 15, August 15, and November 15 of each year, provided that if such date falls on a weekend or holiday, the Quarterly Vesting Date shall be the first business day after such date.

Content

These restricted stock units ("RSUs") vest as to 1/8th of the total number of shares (rounded down to the next whole number of shares) on the second Quarterly Vesting Date (as defined below) following March 9, 2026, and as to 1/8th of the total number of shares (rounded down to the next whole number of shares) on the next seven Quarterly Vesting Dates, such that all of the shares subject to the RSUs shall be vested on the last Quarterly Vesting Date, subject to the reporting person's continuous employment. "Quarterly Vesting Date" means March 1, May 15, August 15, and November 15 of each year, provided that if such date falls on a weekend or holiday, the Quarterly Vesting Date shall be the first business day after such date.