Atara director granted 12,000 RSUs

HEIDEN WILLIAM K reported acquisition or exercise transactions in this Form 4 filing.

Rhea-AI Filing Summary

HEIDEN WILLIAM K reported acquisition or exercise transactions in this Form 4 filing.

Atara Biotherapeutics director William K. Heiden received a grant of 12,000 shares of Common Stock in the form of restricted stock units as compensation. The award was recorded at a price of $0.00 per share and is not an open-market purchase.

These restricted stock units will vest on the earlier of June 9, 2027 or the date of the next annual meeting of stockholders, provided he maintains continuous service. Following this grant, Heiden directly holds 34,188 shares of Atara Biotherapeutics common stock.

Insider Trade Summary

Grant/Award: 12,000 shares

Grant/Award 1 txn

Insider HEIDEN WILLIAM K

Role Director

Type	Security	Shares	Price	Value
Grant/Award	Common Stock	12,000	$0.00	$0.00

Holdings After Transaction: Common Stock — 34,188 shares (Direct)

Footnotes (1)

1. F1. These restricted stock units shall vest on the earlier of June 9, 2027 or the date of the next annual meeting of stockholders, subject to the Reporting Person's continuous service.

Key Figures

RSU grant size: 12,000 shares Grant price: $0.00 per share Shares after transaction: 34,188 shares +1 more

4 metrics

RSU grant size 12,000 shares Restricted stock units of Common Stock granted to director

Grant price $0.00 per share Recorded price for the RSU award

Shares after transaction 34,188 shares Total Common Stock held directly after grant

RSU vesting date June 9, 2027 Latest possible vesting date, or earlier at next annual meeting

Key Terms

restricted stock units, continuous service, grant, award, or other acquisition

3 terms

restricted stock units financial

"These restricted stock units shall vest on the earlier of June 9, 2027 or the date of the next annual meeting of stockholders"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

continuous service financial

"subject to the Reporting Person's continuous service"

grant, award, or other acquisition financial

"transaction_code_description: Grant, award, or other acquisition"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did Atara Biotherapeutics (ATRA) report for William K. Heiden?

Atara Biotherapeutics reported that director William K. Heiden received a grant of 12,000 restricted stock units of Common Stock. The grant is a compensation award rather than an open-market purchase and was recorded at a price of $0.00 per share.

When do William K. Heiden’s new Atara Biotherapeutics (ATRA) restricted stock units vest?

The 12,000 restricted stock units granted to William K. Heiden vest on the earlier of June 9, 2027 or the date of Atara Biotherapeutics’ next annual meeting of stockholders, provided he maintains continuous service with the company.

How many Atara Biotherapeutics (ATRA) shares does William K. Heiden hold after this Form 4 transaction?

After this grant, director William K. Heiden is reported to directly hold 34,188 shares of Atara Biotherapeutics Common Stock. This figure reflects his position immediately following the 12,000-share restricted stock unit award.

Was William K. Heiden’s Atara Biotherapeutics (ATRA) Form 4 transaction an open-market buy or sell?

The Form 4 shows a grant or award acquisition, not an open-market buy or sell. The 12,000 shares were received as restricted stock units at a stated price of $0.00 per share, consistent with an equity compensation award.

What conditions apply to William K. Heiden’s new Atara Biotherapeutics (ATRA) restricted stock units?

The restricted stock units granted to William K. Heiden will vest only if he maintains continuous service with Atara Biotherapeutics until the earlier of June 9, 2027 or the date of the company’s next annual meeting of stockholders.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 06/11/2026 - 04:37 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

HEIDEN WILLIAM K

(Last) (First) (Middle)

C/O ATARA BIOTHERAPEUTICS, INC.

1280 RANCHO CONEJO BOULEVARD

(Street)

THOUSAND OAKS CALIFORNIA 91320

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Atara Biotherapeutics, Inc. [ ATRA ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/09/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	06/09/2026		A		12,000(1)	A	$0	34,188	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. These restricted stock units shall vest on the earlier of June 9, 2027 or the date of the next annual meeting of stockholders, subject to the Reporting Person's continuous service.

	/s/ John Chao, Attorney-in-Fact for William Heiden	06/11/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)