EcoR1 Capital, LLC bought $4.7M of ATRA
owner at Atara Biotherapeutics, Inc.. 507,407 shares at an average of $9.35, traded May 7, 2026, filed May 11, 2026.
Score components
- +12Role10% owner
- +25Trade size$4.7M at market
- +6Relative to holdingsHoldings up 49%
- +8Price context45% below the 52-week high
- 0ClusterNo other insider buying within 14 days
- 0Repeat buyingFirst buy in 90 days
- 0Track recordToo few past buys to judge (0 with prices)
- -5Outside holderA 10% owner who is not an officer or director
What happened after comparable buys
Same side and tier, against the S&P 500, at 1, 3 and 6 months. Shown to Pro users; the whole table is on the backtest page.
This signal so far: 1m +12.3%, 3m -1.9%, 6m -.
Price around the trade, and since
From a quarter before the trade to today. The arrow is the trade, the circle the day the filing reached EDGAR, which is the first day anyone outside could act; the dotted line is the S&P 500 rebased to that day's close.
Daily candles, adjusted for splits and dividends. Green arrows are insider buys, red are sells, sized by value; the dashed line is the close on the filing day, the dotted line SPY rebased to it.Charts by TradingView Lightweight Charts™
Rows in this filing
Every transaction in Form 4 0000935836-26-000239, as filed. Open on EDGAR
| Date | Transaction | Shares | Price | Value | Holdings after | Filed |
|---|---|---|---|---|---|---|
| May 7, 2026 | POpen-market purchase Common Stockindirect: See Note | +507,407 | $9.35 | $4.7M | 1,552,000 | May 11, 2026 |
Related signals
Other insiders at Atara Biotherapeutics, Inc. and this insider’s other filings.
| Score | Company | Insider | Value | Holdings | Filed |
|---|---|---|---|---|---|
| 50Moderate | ATRAbuy Atara Biotherapeutics, Inc. | Brian N Cherry director | $1000k 104,166 shares | +167% | |
| 30Weak | Atara Biotherapeutics, Inc. | Yanina Grant-Huerta Chief Accounting Officer | $22k 2,414 shares | -5% | |
| 47Moderate | Atara Biotherapeutics, Inc. | AnhCo Nguyen President and CEO | $48k 5,241 shares | -4% | |
| 60Notable | Atara Biotherapeutics, Inc. | James Huang director, owner | $3.2M 313,446 shares | -24% | |
| 33Weak | Atara Biotherapeutics, Inc. | AnhCo Nguyen President and CEO | $15k 2,996 shares | -5% | |
| 23Weak | Atara Biotherapeutics, Inc. | Yanina Grant-Huerta Chief Accounting Officer | $11k 2,104 shares | -6% | |
| 33Weak | ATRAsell Atara Biotherapeutics, Inc. | James Huang director, owner | $489k 80,554 shares | -6% | |
| 23Weak | Atara Biotherapeutics, Inc. | Yanina Grant-Huerta Chief Accounting Officer | $24k 1,804 shares | -5% | |
| 39Weak | Atara Biotherapeutics, Inc. | AnhCo Nguyen President and CEO | $38k 2,915 shares | -4% | |
| 23Weak | Atara Biotherapeutics, Inc. | Yanina Grant-Huerta Chief Accounting Officer | $21k 1,809 shares | -5% |
Not investment advice. Scores and forward returns are decision support built from public SEC filings and past prices; they describe what happened after comparable filings, not what will happen after this one. Do your own research and size your risk.