Insider trades › EcoR1 Capital, LLC
EcoR1 Capital, LLC
A corporate insider: an officer, director or owner of more than 10% of a company. Insiders report their trades to the SEC on Form 4The form insiders use to report each purchase or sale of their company's stock. It is due within two business days of the trade. · Last filing May 11, 2026
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Using 13F.ai, list EcoR1 Capital, LLC's open-market buys and sells across companies in the last two years, with the Form 4 links.
Using 13F.ai, how did the stocks EcoR1 Capital, LLC bought perform after the purchase compared with the S&P 500?
Using 13F.ai, are other insiders at the same companies buying or selling at the same time as EcoR1 Capital, LLC?
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Buying and selling by quarter
Dollars bought and sold on the open market over the last two years.
Bought Sold
By trade date, using the shares and price reported for each trade. Stock grants, option exercises and shares withheld for tax are left out.
Roles
The companies where this person reports as an insider, and their position at each, most recent first.
| ATRA Atara Biotherapeutics, Inc. | 10% owner | May 11, 2026 |
| TRAX First Tracks Biotherapeutics, Inc. | 10% owner | Apr 22, 2026 |
| AKTS Aktis Oncology, Inc. | Director, 10% owner | Jan 8, 2026 |
| ADAP Adaptimmune Therapeutics PLC | 10% owner | Jul 30, 2025 |
| ZYME Zymeworks Inc. | Director, 10% owner | May 19, 2025 |
| ITOS iTeos Therapeutics, Inc. | 10% owner | May 16, 2025 |
| PRTA Prothena Corporation plc | 10% owner | May 6, 2025 |
| ANAB AnaptysBio, Inc. | Director, 10% owner | Jan 2, 2025 |
| MRSN Mersana Therapeutics, Inc. | 10% owner | Dec 23, 2024 |
| TNGX Tango Therapeutics, Inc. | 10% owner | Nov 8, 2024 |
Roles come from the filings themselves and can change over time.
Latest open-market trades
Purchases and sales at every company, most recent filing first.
| How the stock has done since the trade date, measured against the S&P 500 over the same days. It describes the stock, not the trader's actual gain or loss. | Filing | ||||||
|---|---|---|---|---|---|---|---|
| May 7, 2026 | ATRA Atara Biotherapeutics, Inc. | Buy | 507,407 | $9.35 | $4.7M | -25.6% | Form 4 ↗ |
| Apr 20, 2026 | TRAX First Tracks Biotherapeutics, Inc. | Sale | 4.71M | $13.81 | $65.0M | +146.8% | Form 4 ↗ |
| Jul 30, 2025 | ADAP Adaptimmune Therapeutics PLC | Sale | 27.43M | $0.10 | $2.7M | -52.9% | Form 4 ↗ |
| Jul 29, 2025 | ADAP Adaptimmune Therapeutics PLC | Sale | 2.69M | $0.10 | $268.7K | -55.5% | Form 4 ↗ |
| Jul 28, 2025 | ADAP Adaptimmune Therapeutics PLC | Sale | 33.93M | $0.11 | $3.7M | -52.7% | Form 4 ↗ |
| May 19, 2025 | ZYME Zymeworks Inc. | Buy | 5,919 | $11.78 | $69.7K | +95.2% | Form 4 ↗ |
| May 15, 2025 | ZYME Zymeworks Inc. | Buy | 49,502 | $11.43 | $565.8K | +99.8% | Form 4 ↗ |
| May 15, 2025 | ITOS iTeos Therapeutics, Inc. | Buy | 3.30M | $8.00 | $26.4M | +18.1% | Form 4 ↗ |
| May 14, 2025 | ITOS iTeos Therapeutics, Inc. | Buy | 1.66M | $7.41 | $12.3M | +23.8% | Form 4 ↗ |
| May 6, 2025 | PRTA Prothena Corporation plc | Sale | 1.98M | $7.64 | $15.2M | -24.0% | Form 4 ↗ |
| May 5, 2025 | PRTA Prothena Corporation plc | Sale | 977,693 | $8.11 | $7.9M | -32.9% | Form 4 ↗ |
| May 2, 2025 | PRTA Prothena Corporation plc | Sale | 3.32M | $8.36 | $27.7M | -37.1% | Form 4 ↗ |
| Apr 17, 2025 | ZYME Zymeworks Inc. | Buy | 54,760 | $11.52 | $630.8K | +84.3% | Form 4 ↗ |
| Apr 16, 2025 | ZYME Zymeworks Inc. | Buy | 73,953 | $11.16 | $825.3K | +89.7% | Form 4 ↗ |
| Apr 2, 2025 | ZYME Zymeworks Inc. | Buy | 74,360 | $11.85 | $881.2K | +86.5% | Form 4 ↗ |
| Apr 1, 2025 | ZYME Zymeworks Inc. | Buy | 48,658 | $11.60 | $564.4K | +91.3% | Form 4 ↗ |
| Mar 31, 2025 | ZYME Zymeworks Inc. | Buy | 4,397 | $11.75 | $51.7K | +85.5% | Form 4 ↗ |
| Mar 26, 2025 | ZYME Zymeworks Inc. | Buy | 43,848 | $12.24 | $536.7K | +79.8% | Form 4 ↗ |
| Mar 25, 2025 | ZYME Zymeworks Inc. | Buy | 53,501 | $12.91 | $690.7K | +73.9% | Form 4 ↗ |
| Mar 24, 2025 | ZYME Zymeworks Inc. | Buy | 22,689 | $13.08 | $296.8K | +69.7% | Form 4 ↗ |
| Mar 21, 2025 | ZYME Zymeworks Inc. | Buy | 31,033 | $12.78 | $396.6K | +72.5% | Form 4 ↗ |
| Mar 20, 2025 | ZYME Zymeworks Inc. | Buy | 73,476 | $12.93 | $950.0K | +69.5% | Form 4 ↗ |
| Mar 19, 2025 | ZYME Zymeworks Inc. | Buy | 58,306 | $12.64 | $737.0K | +72.1% | Form 4 ↗ |
| Mar 18, 2025 | ZYME Zymeworks Inc. | Buy | 113,880 | $12.65 | $1.4M | +78.2% | Form 4 ↗ |
| Mar 17, 2025 | ZYME Zymeworks Inc. | Buy | 56,277 | $12.23 | $688.3K | +75.6% | Form 4 ↗ |
| Jan 17, 2025 | ZYME Zymeworks Inc. | Buy | 19,748 | $13.87 | $273.9K | +62.8% | Form 4 ↗ |
| Jan 16, 2025 | ZYME Zymeworks Inc. | Buy | 121,681 | $13.89 | $1.7M | +60.1% | Form 4 ↗ |
| Jan 15, 2025 | ZYME Zymeworks Inc. | Buy | 39,029 | $14.01 | $546.8K | +59.6% | Form 4 ↗ |
| Jan 14, 2025 | ZYME Zymeworks Inc. | Buy | 54,500 | $13.56 | $739.0K | +63.1% | Form 4 ↗ |
| Jan 13, 2025 | ZYME Zymeworks Inc. | Buy | 74,125 | $13.39 | $992.5K | +58.2% | Form 4 ↗ |
| Jan 10, 2025 | ZYME Zymeworks Inc. | Buy | 204,098 | $13.13 | $2.7M | +68.5% | Form 4 ↗ |
| Jan 8, 2025 | ZYME Zymeworks Inc. | Buy | 21,021 | $14.07 | $295.8K | +57.7% | Form 4 ↗ |
| Jan 2, 2025 | ANAB AnaptysBio, Inc. | Buy | 6,646 | $12.95 | $86.1K | +390.2% | Form 4 ↗ |
| Jan 2, 2025 | ZYME Zymeworks Inc. | Buy | 157,880 | $14.78 | $2.3M | +48.5% | Form 4 ↗ |
| Dec 31, 2024 | ANAB AnaptysBio, Inc. | Buy | 13,268 | $12.93 | $171.6K | +395.3% | Form 4 ↗ |
| Dec 31, 2024 | ZYME Zymeworks Inc. | Buy | 146,501 | $14.57 | $2.1M | +50.5% | Form 4 ↗ |
| Dec 30, 2024 | ANAB AnaptysBio, Inc. | Buy | 65,184 | $12.92 | $842.2K | +396.5% | Form 4 ↗ |
| Dec 30, 2024 | ZYME Zymeworks Inc. | Buy | 58,988 | $14.47 | $853.6K | +52.6% | Form 4 ↗ |
| Dec 27, 2024 | ZYME Zymeworks Inc. | Buy | 101,659 | $14.49 | $1.5M | +54.2% | Form 4 ↗ |
| Dec 26, 2024 | ZYME Zymeworks Inc. | Buy | 16,692 | $14.38 | $240.0K | +55.5% | Form 4 ↗ |
| Dec 24, 2024 | ZYME Zymeworks Inc. | Buy | 11,958 | $14.12 | $168.8K | +60.1% | Form 4 ↗ |
| Dec 23, 2024 | ZYME Zymeworks Inc. | Buy | 251,502 | $14.25 | $3.6M | +56.9% | Form 4/A ↗ |
| Dec 20, 2024 | ZYME Zymeworks Inc. | Buy | 704,488 | $14.08 | $9.9M | +58.0% | Form 4/A ↗ |
| Dec 19, 2024 | ZYME Zymeworks Inc. | Buy | 298,818 | $13.53 | $4.0M | +64.5% | Form 4/A ↗ |
| Nov 7, 2024 | TNGX Tango Therapeutics, Inc. | Sale | 62,318 | $3.29 | $205.0K | +774.4% | Form 4 ↗ |
| Nov 7, 2024 | TNGX Tango Therapeutics, Inc. | Sale | 1.14M | $2.92 | $3.3M | +774.4% | Form 4 ↗ |
| Nov 6, 2024 | TNGX Tango Therapeutics, Inc. | Sale | 1.49M | $3.28 | $4.9M | +659.4% | Form 4 ↗ |
Each row links to its Form 4. Since trade compares the stock’s move from the close on the trade date (or the next trading day) to its latest close with the S&P 500 over the same days, adjusted for splits and excluding dividends. It describes the stock, not what the trader made: we don’t know their purchase price, position size or later sales. A dash means the trade isn’t matched to a listed stock, or there is no closing price after it yet.
When several people report on the same filing, we list it under the first one named, so trades by someone usually listed second may be missing here. Information, not investment advice: see the disclaimer.