EcoR1 Capital, LLC reported 29 positions worth $2.01B for the quarter ended Jun 30, 2026, up 3.4% on the prior quarter. It opened 8 new positions, added to 3, trimmed 4 and exited 5. Its largest holding is Zymeworks Inc. at 29.9% of the portfolio.
Reported 13F market value at each quarter end. A change mixes trading with price moves in the positions held.
Dollar value of shares bought and sold each quarter, at that quarter’s price. It counts trading only, not price changes.
How many positions were opened, added to, trimmed or closed each quarter.
Share of reported value in each sector at every quarter end.
| Holding | Change | Change % | Trade Value | Weight |
|---|---|---|---|---|
| TRAX First Tracks Biotherapeutics, Inc. | +3.17M | – | $63.87M | 3.18% |
| CGON CG Oncology, Inc. | +392.3K | +35.6% | $27.87M | 5.28% |
| FULC Fulcrum Therapeutics, Inc. | +6.55M | – | $23.97M | 1.19% |
| LEGN Legend Biotech Corp | +800.0K | – | $23.10M | 1.15% |
| STOK Stoke Therapeutics, Inc. | +635.0K | +635.0% | $20.78M | 1.2% |
| ATRA Atara Biotherapeutics, Inc. | +1.45M | +1,458.3% | $16.67M | 0.886% |
| AURA Aura Biosciences, Inc. | +1.67M | – | $11.83M | 0.588% |
| ODTX Odyssey Therapeutics, Inc. | +555.6K | – | $10.39M | 0.517% |
| PHVS Pharvaris N.V. | +235.0K | – | $8.13M | 0.404% |
| NRIX Nurix Therapeutics, Inc. | +270.0K | – | $6.55M | 0.326% |
| Holding | Change | Change % | Trade Value | Weight |
|---|---|---|---|---|
| JAZZ Jazz Pharmaceuticals plc | -1.71M | -100.0% | $322.61M | Exited |
| XNCR Xencor Inc | -2.18M | -100.0% | $26.33M | Exited |
| RLAY Relay Therapeutics, Inc. | -1.21M | -63.4% | $22.58M | 0.649% |
| MBX MBX Biosciences, Inc. | -388.5K | -50.0% | $21.45M | 1.07% |
| ERAS Erasca, Inc. | -570.0K | -63.3% | $10.44M | 0.301% |
| REPL Replimune Group, Inc. | -1.00M | -100.0% | $7.65M | Exited |
| MREO Mereo BioPharma Group plc | -12.37M | -92.5% | $3.93M | 0.016% |
| PRLD Prelude Therapeutics Inc | -947.0K | -100.0% | $3.24M | Exited |
| IBIO iBio, Inc. | -1.58M | -100.0% | $3.01M | Exited |
| Holding | Shares | Trade Value | Weight |
|---|---|---|---|
| TRAX First Tracks Biotherapeutics, Inc. | +3.17M | $63.87M | 3.18% |
| FULC Fulcrum Therapeutics, Inc. | +6.55M | $23.97M | 1.19% |
| LEGN Legend Biotech Corp | +800.0K | $23.10M | 1.15% |
| AURA Aura Biosciences, Inc. | +1.67M | $11.83M | 0.588% |
| ODTX Odyssey Therapeutics, Inc. | +555.6K | $10.39M | 0.517% |
| PHVS Pharvaris N.V. | +235.0K | $8.13M | 0.404% |
| NRIX Nurix Therapeutics, Inc. | +270.0K | $6.55M | 0.326% |
| AARD Aardvark Therapeutics, Inc. | +396.2K | $2.28M | 0.113% |
| # | Activity | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| 1 | ZYME Zymeworks Inc. | Healthcare | 22.97M | $600.45M | 29.86% | 0 | 0.0% | Unchanged | 31.47% |
| 2 | ANAB Anaptysbio, Inc | Healthcare | 7.88M | $531.91M | 26.45% | 0 | 0.0% | Unchanged | 27.14% |
| 3 | AKTS Aktis Oncology, Inc. | Healthcare | 4.82M | $155.49M | 7.73% | 0 | 0.0% | Unchanged | 8.72% |
| 4 | CGON CG Oncology, Inc. | Healthcare | 1.49M | $106.17M | 5.28% | +392.3K | +35.6% | Added | 1.69% |
| 5 | ETON Eton Pharmaceuticals, Inc. | Healthcare | 2.17M | $78.62M | 3.91% | 0 | 0.0% | Unchanged | 7.68% |
| 6 | CRSP CRISPR Therapeutics AG | Healthcare | 1.39M | $75.77M | 3.77% | 0 | 0.0% | Unchanged | 1.44% |
| 7 | ORIC Oric Pharmaceuticals, Inc. | Healthcare | 6.73M | $72.87M | 3.62% | 0 | 0.0% | Unchanged | 6.23% |
| 8 | TRAX First Tracks Biotherapeutics, Inc. | Healthcare | 3.17M | $63.87M | 3.18% | +3.17M | – | New | 8.97% |
| 9 | LKFT Lakefront Biotherapeutics NV | Healthcare | 1.67M | $49.98M | 2.49% | 0 | 0.0% | Unchanged | 2.53% |
| 10 | NGNE Neurogene Inc. | Healthcare | 1.27M | $39.98M | 1.99% | 0 | 0.0% | Unchanged | 5.64% |
| 11 | STOK Stoke Therapeutics, Inc. | Healthcare | 735.0K | $24.05M | 1.2% | +635.0K | +635.0% | Added | 1.11% |
| 12 | FULC Fulcrum Therapeutics, Inc. | Healthcare | 6.55M | $23.97M | 1.19% | +6.55M | – | New | 8.59% |
| 13 | LEGN Legend Biotech Corp | Healthcare | 800.0K | $23.10M | 1.15% | +800.0K | – | New | 0.43% |
| 14 | BBOT BridgeBio Oncology Therapeutics, Inc. | Healthcare | 2.82M | $21.51M | 1.07% | 0 | 0.0% | Unchanged | 3.53% |
| 15 | MBX MBX Biosciences, Inc. | Healthcare | 388.5K | $21.45M | 1.07% | -388.5K | -50.0% | Reduced | 0.81% |
Tip. Select a row to see that position’s full history at EcoR1 Capital.
As of its Q2 2026 13F filing, EcoR1 Capital, LLC’s five largest positions were Zymeworks Inc. (ZYME) at 29.9%, Anaptysbio, Inc (ANAB) at 26.4%, Aktis Oncology, Inc. (AKTS) at 7.7%, CG Oncology, Inc. (CGON) at 5.3%, Eton Pharmaceuticals, Inc. (ETON) at 3.9% of the reported portfolio.
EcoR1 Capital, LLC reported a 13F portfolio worth $2.01B across 29 positions for Q2 2026. That is up 3.4% from the previous quarter.
Its largest purchases by value were First Tracks Biotherapeutics, Inc. ($63.87M), CG Oncology, Inc. ($27.87M), Fulcrum Therapeutics, Inc. ($23.97M). It opened 8 new positions.
Its largest sales by value were Jazz Pharmaceuticals plc ($322.61M), Xencor Inc ($26.33M), Relay Therapeutics, Inc. ($22.58M). It exited 5 positions entirely.
From the Form 13F-HR reports EcoR1 Capital, LLC files with the SEC each quarter, within 45 days of quarter end. A 13F lists long positions in US-listed equities and options; it excludes short positions, cash, bonds and most non-US holdings.
13F data reflects long positions in US-listed equities and options as reported to the SEC up to 45 days after quarter end. It excludes short positions, cash, bonds and most non-US securities, so it is not a complete picture of a manager’s assets.