Atara Biotherapeutics (ATRA) Form 144: RSU Settlement and Proposed Sale

Rhea-AI Filing Summary

Atara Biotherapeutics (ATRA) filed a Form 144 reporting a proposed sale of 2,048 shares of common stock on or about 08/18/2025 through Morgan Stanley Smith Barney LLC on NASDAQ with an aggregate market value of $25,169.92. The filing shows those shares were acquired on 08/15/2025 as settlement of vested restricted stock units issued under an S-8 registration plan, with payment noted as equity compensation for services rendered. The filer also reported a prior sale on 05/16/2025 of 2,218 shares for gross proceeds of $15,000.33. The notice includes the standard representation that the seller is not aware of undisclosed material adverse information about the issuer.

Positive

• Acquisition source disclosed: Shares were acquired by settlement of vested RSUs under an S-8 registration plan, clarifying the origin as equity compensation.
• Broker and timing provided: Broker (Morgan Stanley Smith Barney LLC) and approximate sale date (08/18/2025) are specified, supporting transaction transparency.

Negative

• Insider proposes to sell shares: The filer intends to sell 2,048 shares, which may be viewed negatively by some investors despite being routine.
• Limited issuer detail: The filing does not include additional company financial information or context about the reason for sale beyond compensation settlement.

Insights

Securities Compliance Analyst

TL;DR: Routine insider sale from vested RSUs reported under Form 144; disclosure aligns with Rule 144 requirements.

The filing documents a proposed disposition of newly vested equity through a broker and includes prior short-term sales. From a compliance perspective, the form supplies the required acquisition details, nature of acquisition (settlement of RSUs under an S-8), and the broker and timing for the proposed sale. The representation about absence of undisclosed material adverse information is standard. The filing appears procedural and consistent with Rule 144 notice obligations.

Equity Compensation Specialist

TL;DR: This is a routine monetization of vested RSUs; shows equity compensation being realized by the holder.

The record that 4,760 shares were acquired on 08/15/2025 via settlement of vested RSUs and that 2,048 shares are proposed for sale shortly thereafter indicates an employee or service-provider realizing value from equity compensation. The disclosure of the broker, planned sale date, and past short-term sale is useful for documenting transfer and liquidity events tied to compensation plans. No additional performance or company-specific financial data is provided in the filing.

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

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	2048	25169.92	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			4760	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
Yanina Grant-Huerta 1280 Rancho Conejo Boulevard Thousand Oaks CA 91320	Common Stock	05/16/2025	2218	15000.33

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 ATRA Form 144 report?

The Form 144 reports a proposed sale of 2,048 Atara Biotherapeutics (ATRA) common shares on or about 08/18/2025 through Morgan Stanley Smith Barney LLC with an aggregate market value of $25,169.92.

How were the shares acquired for the ATRA sale?

The shares were acquired on 08/15/2025 by settlement of vested RSUs issued under an S-8 registration plan and paid as equity compensation for services rendered.

Has the filer sold ATRA shares recently?

Yes. The filing discloses a prior sale on 05/16/2025 of 2,218 shares for gross proceeds of $15,000.33.

On which exchange will the ATRA shares be sold?

The proposed sale is to occur on NASDAQ via Morgan Stanley Smith Barney LLC.

Does the form indicate any undisclosed material information about ATRA?

The person for whose account the securities are to be sold represents that they do not know of any material adverse information regarding the issuer that has not been publicly disclosed.

How many shares were acquired in the RSU settlement reported?

The acquisition entry for the RSU settlement shows 4,760 shares were acquired on 08/15/2025.