Atara director buys 104K shares at $9.60

A director of Atara Biotherapeutics purchased 104,166 shares in a direct, non‑plan transaction, raising his holdings to 166,486 shares.

Rhea-AI Filing Summary

Atara Biotherapeutics, Inc. (ATRA) director Brian N. Cherry reported purchasing common stock of the company. On September 4, 2026, he acquired 104,166 shares of Atara common stock at $9.60 per share, increasing his directly held position to 166,486 shares.

The shares were purchased from Atara through its sales agent under a Sales Agreement dated November 1, 2023. No Rule 10b5-1 trading plan is indicated for this transaction.

Insider Trade Summary

Net Buyer: 104,166 shares

Net Buy 1 txn

Insider Cherry Brian N

Role Director

Bought 104,166 shs ($1000K)

Type	Security	Shares	Price	Value
Purchase	Common Stock F1	104,166	$9.60	$1000K

Holdings After Transaction: Common Stock — 166,486 shares (Direct)

Footnotes (1)

1. F1. Represents shares purchased by the Reporting Person from the Issuer, through its sales agent, pursuant to that certain Sales Agreement, dated November 1, 2023, by and between the Issuer and TD Securities (USA) LLC.

Key Figures

Shares purchased: 104,166 shares Purchase price per share: $9.60 Shares held after transaction: 166,486 shares +2 more

5 metrics

Shares purchased 104,166 shares Common stock acquired by director on September 4, 2026

Purchase price per share $9.60 Price paid for Atara common stock on September 4, 2026

Shares held after transaction 166,486 shares Director’s direct holdings of Atara common stock after the purchase

Net buy shares 104,166 shares Net change in reported holdings from this Form 4

Buy transactions 1 transaction Number of purchase transactions reported in this Form 4

Key Terms

Sales Agreement, sales agent, Power of Attorney

3 terms

Sales Agreement financial

"pursuant to that certain Sales Agreement, dated November 1, 2023, by and between"

A sales agreement is a written contract that sets out the terms for selling goods, services, or assets, specifying price, delivery, payment schedule and responsibilities of each side. For investors it matters because it creates a predictable stream of revenue or cash obligations, clarifies timing and risk, and can change a company’s value or forecasts much like a signed order turns a customer’s verbal intent into a firm commitment.

sales agent financial

"purchased by the Reporting Person from the Issuer, through its sales agent"

A sales agent is an individual or firm authorized to sell a company’s products or services on its behalf, typically paid by commission or fees rather than a fixed salary. For investors, who a company uses to reach customers and how well those agents perform affects revenue growth and profit margins — like hiring local independent sellers to expand into new neighborhoods without building stores — so agent quality and cost matter to future cash flow and valuation.

Power of Attorney regulatory

"Exhibit 24 - Power of Attorney"

A power of attorney is a legal document that allows one person to make decisions and act on behalf of another person, often in financial or legal matters. It’s like giving someone a trusted helper or agent the authority to handle important tasks if you are unable to do so yourself. This matters to investors because it can impact how their assets are managed or transferred if they become unable to oversee their affairs.

FAQ

What insider transaction did Atara Biotherapeutics (ATRA) report on this Form 4?

The filing reports that director Brian N. Cherry purchased 104,166 shares of Atara Biotherapeutics common stock on September 4, 2026 in a non-derivative transaction, identified as a purchase in an open market or private transaction.

At what price did the Atara Biotherapeutics (ATRA) director buy shares?

The director purchased Atara Biotherapeutics common stock at $9.60 per share on September 4, 2026. This per-share price applies to the entire reported purchase of 104,166 shares.

How many Atara Biotherapeutics (ATRA) shares does the director hold after this transaction?

Following the reported purchase, director Brian N. Cherry directly holds 166,486 shares of Atara Biotherapeutics common stock. This figure reflects his position immediately after the September 4, 2026 transaction.

Was the Atara Biotherapeutics (ATRA) insider trade made under a Rule 10b5-1 plan?

No. The Form 4 indicates that no Rule 10b5-1 trading plan applies to this transaction, meaning the purchase was not reported as being made pursuant to a pre-arranged trading plan.

From whom were the Atara Biotherapeutics (ATRA) shares purchased in this Form 4 transaction?

According to the footnote, the shares were purchased from Atara Biotherapeutics itself, through its sales agent TD Securities (USA) LLC, under a Sales Agreement dated November 1, 2023.

What is the nature of the security in this Atara Biotherapeutics (ATRA) Form 4?

The reported transaction involves common stock of Atara Biotherapeutics, Inc. It is classified as a non-derivative security in the Form 4 data.

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Available on EDGAR 09/04/2026 - 06:20 PM Accepted by SEC EDGAR 09/04/2026 - 06:20 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^*

Cherry Brian N

(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)
09/04/2026

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	09/04/2026		P		104,166(1)	A	$9.6	166,486	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. Represents shares purchased by the Reporting Person from the Issuer, through its sales agent, pursuant to that certain Sales Agreement, dated November 1, 2023, by and between the Issuer and TD Securities (USA) LLC.

Remarks:

Exhibit List: Exhibit 24 - Power of Attorney

	/s/ Brian Cherry	09/04/2026
	** 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)