Atara Biotherape SEC Filings

Atara Biotherapeutics Chief Accounting Officer Yanina Grant-Huerta reported the sale of 2,414 shares of common stock. The shares were sold on May 18, 2026 at a weighted average price of $9.1286 per share, in multiple trades between $9.12 and $9.40.

According to the disclosure, these shares were sold automatically to satisfy tax withholding obligations tied to the vesting of previously granted restricted stock units under a sale-to-cover provision. After the transaction, Grant-Huerta directly holds 49,636 shares of Atara common stock.

ATRA submitted a notice for the settlement/sale of 13,887 shares of Common Stock on 05/15/2026, described as settlement of vested RSUs issued under an S-8 registration plan. The excerpt also shows a prior sale of 2,996 shares on 03/02/2026.

ATRA submitted a Form 144 notice reporting the settlement and disposition of Common Stock tied to employee equity. The filing shows 6,393 shares settled on 05/15/2026 as payment for vested RSUs issued under an S-8 registration, and a prior sale of 2,104 shares on 03/02/2026.

Redmile Group and related entities updated their ownership disclosure for Atara Biotherapeutics. They report beneficial ownership of 950,994 shares of common stock, representing 9.9% of the class, including shares issuable from pre-funded warrants subject to a 9.99% Beneficial Ownership Limitation.

The filing explains that this increase in deemed beneficial ownership results from a higher number of Atara shares outstanding, which raised the maximum shares issuable upon warrant exercise. Redmile-managed funds directly hold 441,701 common shares and 3,412,843 pre-funded warrants, of which 509,293 shares are currently counted toward beneficial ownership under the limitation.

Atara Biotherapeutics reports a reported 8.56% ownership position held by Adage Capital Management and affiliated individuals.

Adage Capital Management, L.P., together with Robert Atchinson and Phillip Gross, states shared dispositive and voting power over 700,000 shares of Common Stock. The filing calculates the percentage using 8,178,114 shares outstanding as of March 10, 2026. The statement is a joint Schedule 13G disclosure of beneficial ownership and identifies the Reporting Persons and their business addresses.

Atara Biotherapeutics amended its sales-agreement prospectus to confirm it may continue at-the-market sales up to an aggregate offering price of $79,269,007 under the existing Sales Agreement with TD Securities (USA) LLC. This supplement, dated May 12, 2026, relies on a staff interpretation addressing Form S-3 eligibility after a Section 10(a)(3) update.

The supplement states the company may offer and sell shares of Common Stock from time to time through the named sales agent, and that the full amount remaining under the Sales Agreement is available despite a change in the Form S-3 eligibility criterion referenced in General Instruction I.B.1 because the company qualifies under General Instruction I.B.6.

Atara Biotherapeutics, Inc. reported Q1 2026 commercialization revenue of $516,000, sharply lower than $98.1 million a year earlier, when large milestone payments were recognized. The company posted a net loss of $4.1 million, compared with net income of $38.0 million in Q1 2025.

Total assets were $20.0 million and cash and cash equivalents were $8.4 million as of March 31, 2026. Total liabilities were $57.3 million, including $41.5 million related to the sale of future Ebvallo revenues, resulting in a stockholders’ deficit of $37.3 million.

The company states that existing cash and investments will not fund planned operations for 12 months after issuance of these financial statements and concludes that substantial doubt exists about its ability to continue as a going concern. Management plans to seek additional capital, potentially through equity offerings, debt, its ATM program, and strategic transactions, while continuing to rely on Pierre Fabre for global development, manufacturing and commercialization of tab-cel/Ebvallo. Outstanding common shares were 9,010,172 as of May 8, 2026.

Atara Biotherapeutics reported first quarter 2026 results showing a sharp normalization of revenue after a one-time 2025 event and a return to modest losses. Commercialization revenue was $0.5 million, compared with $98.1 million a year earlier, when revenue was accelerated from transferring tab-cel manufacturing to Pierre Fabre.

The company posted a net loss of $4.1 million, or ($0.29) per share, versus net income of $38.0 million in the prior-year period, as operating expenses fell significantly. Research and development expenses dropped to $0.2 million and general and administrative expenses to $3.6 million, reflecting 2025 cost-reduction initiatives.

Cash, cash equivalents and short-term investments were $8.4 million as of March 31, 2026. Atara expects this balance, together with $4.8 million of at-the-market offering proceeds received after quarter end and operating efficiencies, to fund planned operations into mid-2027, despite a capital structure that includes a substantial liability related to the sale of future revenues.

Atara Biotherapeutics’ largest Panacea-affiliated holder updated its ownership report after a significant share sale. Panacea Venture Healthcare Fund II, L.P. and Panacea Opportunity Fund I, L.P. together now report beneficial ownership of 1,318,894 shares of Atara common stock, representing 16.1% of the company’s outstanding shares as of March 10, 2026.

On May 7, 2026, Panacea Venture Healthcare Fund II, L.P. sold 313,446 shares in open market transactions at a weighted average price of $10.0975 per share. James Huang, through Panacea Innovation Limited and related general partners, may be deemed to share beneficial ownership of these holdings but disclaims such beneficial ownership.