Atara director awarded 12,000 RSUs

Fust Matthew K reported acquisition or exercise transactions in this Form 4 filing.

Rhea-AI Filing Summary

Fust Matthew K reported acquisition or exercise transactions in this Form 4 filing.

Atara Biotherapeutics director Matthew K. Fust received an equity award of 12,000 shares of common stock in the form of restricted stock units. The award was granted at no cash cost and will vest on the earlier of June 9, 2027 or the next annual stockholder meeting, subject to his continuous service. Following this grant, he holds 30,188 shares directly.

Insider Trade Summary

Grant/Award: 12,000 shares

Grant/Award 1 txn

Insider Fust Matthew K

Role Director

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

Holdings After Transaction: Common Stock — 30,188 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 Post-grant holdings: 30,188 shares +1 more

4 metrics

RSU grant size 12,000 shares Restricted stock units granted on June 9, 2026

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

Post-grant holdings 30,188 shares Total common stock held directly after the transaction

RSU vesting date June 9, 2027 Vests earlier of this date or next annual meeting

Key Terms

restricted stock units, continuous service, Form 4, Grant, award, or other acquisition

4 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"

Form 4 regulatory

"INSIDER FILING DATA (Form 4):"

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

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?

Atara Biotherapeutics reported that director Matthew K. Fust received 12,000 restricted stock units as an equity award. These units represent common stock granted as compensation, not an open-market purchase, and were issued at no cash cost per share.

When do Matthew K. Fust’s new Atara Biotherapeutics (ATRA) RSUs vest?

The 12,000 restricted stock units granted to Matthew K. Fust vest on the earlier of June 9, 2027 or the date of Atara’s next annual stockholder meeting. Vesting is conditioned on his continuous service with the company until that vesting date.

How many Atara Biotherapeutics (ATRA) shares does Matthew K. Fust own after this grant?

After receiving the 12,000-share restricted stock unit award, Matthew K. Fust’s direct holdings total 30,188 shares of Atara Biotherapeutics common stock. This figure reflects his position following the reported grant-based acquisition on June 9, 2026.

Was Matthew K. Fust’s Atara Biotherapeutics (ATRA) transaction a stock purchase?

No, the transaction was not an open-market stock purchase. It was a grant of 12,000 restricted stock units awarded as compensation at a stated price of $0.00 per share, rather than shares bought on the public market.

What conditions are attached to Matthew K. Fust’s new Atara Biotherapeutics (ATRA) RSUs?

The restricted stock units will vest only if Matthew K. Fust maintains continuous service with Atara. Vesting occurs on the earlier of June 9, 2027 or the company’s next annual meeting of stockholders, according to the grant’s footnote disclosure.

Does this Atara Biotherapeutics (ATRA) Form 4 show any insider share sales?

No insider sales are reported in this Form 4. The filing shows only an acquisition of 12,000 restricted stock units by director Matthew K. Fust, with no corresponding dispositions, sales, gifts, or tax-withholding share transfers disclosed in the transaction summary.

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

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Accepted by SEC EDGAR 06/11/2026 - 04:36 PM EDT 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^*

Fust Matthew 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	30,188	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 Matthew Fust	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)