EcoR1 Capital Makes $4.7M Open Market Purchase of Atara Biotherapeutics Stock
ATRA has more than doubled off its 52-week low of $3.92.
Summary
EcoR1 Capital, a 10% owner, made a substantial open-market purchase of Atara Biotherapeutics shares, investing over $4.7 million, signaling strong conviction amidst recent company challenges.
Key Events · Ownership and Investor Activity · ATRA
-
Major Insider Purchase
EcoR1 Capital, a 10% owner, acquired 507,407 shares of Atara Biotherapeutics common stock for $4,744,255 at an average price of $9.35 per share.
-
Significant Stake
This purchase represents a substantial investment, increasing EcoR1 Capital's indirect holdings to 1,552,000 shares.
-
Timing Amidst Challenges
The transaction occurred on May 7, 2026, the same day Atara Biotherapeutics announced a productive Type A meeting with the FDA, providing a potential path forward for its product, despite recent delisting notices and a going concern warning.
Analysis · ATRA · Life Sciences
EcoR1 Capital, a significant 10% owner, made a substantial open-market purchase of Atara Biotherapeutics stock, investing over $4.7 million. This transaction, representing more than 6% of the company's market capitalization, is particularly notable given the severe challenges Atara Biotherapeutics has recently faced, including a Nasdaq delisting notice, a going concern warning, and prior FDA setbacks. The purchase occurred on the same day the company announced a productive Type A meeting with the FDA, establishing a potential path forward for its lead product. This large investment by a major institutional holder suggests strong conviction in the company's ability to navigate its current difficulties and capitalize on future opportunities.
How filings like this one have moved
In the 30 days to Oct 27, 2026, 45.6% of the 241 measured filings Wiseek scored 9 moved their stock by 5% or more by the next session's close. The median move was -0.73%. These are measured outcomes after filings of this importance, not a forecast for this one.
Measured one observation per ticker per day, after exclusions. Current figures: Filing Impact Tracker · open dataset
At the time of this filing, ATRA was trading at $9.50 on NASDAQ in the Life Sciences sector, with a market capitalization of approximately $74.7M. The 52-week trading range was $3.92 to $19.15. This filing was assessed with positive market sentiment and an importance score of 9 out of 10.