[144] Atara Biotherapeutics, Inc SEC Filing

Rhea-AI Filing Summary

Form 144 notice for Atara Biotherapeutics (ATRA) shows a proposed sale of 3,346 shares of common stock on 08/18/2025 through Morgan Stanley Smith Barney (Executive Services, Sandy, UT), with an aggregate market value of $41,122.34. The shares were acquired as the settlement of vested RSUs issued under an S-8 registration on 08/15/2025; 7,788 shares were received in that settlement and payment was recorded as equity compensation for services rendered. The filer disclosed a prior sale on 05/16/2025 of 3,276 shares for gross proceeds of $22,155.59. The notice includes the required representation that the seller is not aware of undisclosed material adverse information.

Positive

• Timely and complete disclosure of proposed sale under Rule 144, including broker, amount, and market value
• Clear acquisition history showing shares were settled from RSUs under an S-8 registration, with dates and amounts
• Seller certification included that no undisclosed material adverse information is known

Negative

• None.

Insights

Securities Analyst

TL;DR: Routine insider sale of RSU shares; size appears modest and is disclosed under Rule 144.

The filing documents a proposed Rule 144 sale of 3,346 common shares valued at $41,122.34, following an RSU settlement of 7,788 shares on 08/15/2025. A prior sale of 3,276 shares occurred on 05/16/2025 for $22,155.59. This pattern is consistent with scheduled liquidity of vested equity awards rather than an extraordinary corporate event. The transaction was routed through Morgan Stanley Smith Barney as broker, and the filer affirms no undisclosed material adverse information.

Corporate Governance Expert

TL;DR: Disclosure meets compliance expectations; transactions reflect equity compensation monetization.

The notice provides the required details for a proposed sale under Rule 144, including acquisition date, nature of acquisition (settlement of RSUs under an S-8), and prior sales in the past three months. The documentation and broker identification support regulatory transparency. From a governance perspective, these are standard post-vesting dispositions and the seller's certification addresses insider information obligations.

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK
Filer CCC
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer

SEC File Number

Address of Issuer

Phone

Name of Person for Whose Account the Securities are To Be Sold

See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.

Relationship to Issuer

Relationship to Issuer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common Stock	Morgan Stanley Smith Barney LLC Executive Services 200 W Civic Center Drive, 4th Floor Sandy UT 84070	3346	41122.34	7023582	08/18/2025	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common Stock	08/15/2025	Settlement of vested RSUs issued under an S-8 Registration Plan	Issuer			7788	08/15/2025	Equity compensation for services rendered

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
AnhCo Nguyen 1280 Rancho Conejo Boulevard Thousand Oaks CA 91320	Common Stock	05/16/2025	3276	22155.59

144: Remarks and Signature

Remarks

Date of Notice

ATTENTION:

The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.

Signature

ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)

FAQ

What does the Form 144 for Atara Biotherapeutics (ATRA) disclose?

The Form 144 discloses a proposed sale of 3,346 common shares on 08/18/2025 through Morgan Stanley Smith Barney with an aggregate market value of $41,122.34.

How were the shares acquired that are being sold?

The shares were acquired on 08/15/2025 as the settlement of vested RSUs issued under an S-8 registration, with 7,788 shares received in that settlement.

Has the filer sold other Atara (ATRA) shares recently?

Yes; the filing reports a sale on 05/16/2025 of 3,276 shares for gross proceeds of $22,155.59.

Which broker is handling the proposed sale?

The broker listed is Morgan Stanley Smith Barney LLC Executive Services, located in Sandy, UT.

Does the filer state any undisclosed material information about Atara?

The filer represents by signature that they do not know any material adverse information about the issuer that has not been publicly disclosed.