Form 4 for ATRA Atara Biotherapeutics, Inc.

Accepted 2026-03-04 00:00:00 ET · period of report 2026-03-02 · accession 0000905148-26-001143 · SEC index · Original document

Summary rows

Aggregated the way they appear in lists: one row per insider, transaction code and security table.

X	Filed	Traded	Ticker	Insider	Title	Type	Price	Qty	Owned	ΔOwn	Value
M	2026-03-04	2026-03-02	ATRA	Nguyen AnhCo	Pres, CEO, Dir	S - Sale	$5.09	-2,996	62.0K	-5%	-$15.2K

Purchase Sale Sale after option exercise All abbreviations

#	Table	Security	Date	Code	A/D	Shares	Price	Owned after	Own	Exercise / expiry	Underlying	Footnotes
1	Common	Common Stock	2026-03-02	S	D	58	$5.08	64,718	D	—	—	(F2) The sale price of the reporting person's shares represents the weighted average price of all shares sold by a broker on March 2, 2026 on behalf of a group of employees of the Issuer to satisfy the payment of withholding tax liability of such employees.
2	Common	Common Stock	2026-03-02	S	D	1,298	$5.09	63,420	D	—	—	(F2) The sale price of the reporting person's shares represents the weighted average price of all shares sold by a broker on March 2, 2026 on behalf of a group of employees of the Issuer to satisfy the payment of withholding tax liability of such employees.
3	Common	Common Stock	2026-03-02	S	D	198	$5.08	64,776	D	—	—	(F2) The sale price of the reporting person's shares represents the weighted average price of all shares sold by a broker on March 2, 2026 on behalf of a group of employees of the Issuer to satisfy the payment of withholding tax liability of such employees.
4	Common	Common Stock	2026-03-02	S	D	1,442	$5.09	61,978	D	—	—	(F2) The sale price of the reporting person's shares represents the weighted average price of all shares sold by a broker on March 2, 2026 on behalf of a group of employees of the Issuer to satisfy the payment of withholding tax liability of such employees.