EcoR1 Capital, LLC
In its 13F for Q1 2025 (holdings as of March 31, 2025, filed May 15, 2025), EcoR1 Capital, LLC reported 42 stock positions worth $1.7 billion. Its top holding was Apellis Pharmaceuticals (APLS) at 15.5% of the portfolio, followed by Jazz Pharmaceuticals (JAZZ, 12.6%) and Zymeworks (ZYME, 12.2%). Compared with Q4 2024, it opened 5 new positions, sold out of 16, added to 10 and reduced 4. The biggest buy was Anaptysbio (ANAB, shares +0%) and the biggest sale an exit from Arvinas (ARVN).
- Most Recent 13F
- Q2 2026
- Location
- San Francisco, CA
- CIK
- 0001587114
- Portfolio Value
- $1.7B (Q1 2025)
- SEC Filing
- 0000935836-25-000338 ↗ filed May 15, 2025
Holdings Value
Holdings 42 stocks · $1.7B
| APLS Apellis Pharmaceuticals Inc. | 15.47% | 11,895,808 | $260.2M | Add +0.0% |
| JAZZ Jazz Pharmaceuticals PLC | 12.60% | 1,706,469 | $211.9M | No change |
| ZYME Zymeworks Inc. | 12.23% | 17,259,548 | $205.6M | Add +14.8% |
| ANAB Anaptysbio Inc. | 8.71% | 7,880,094 | $146.5M | Add +0.1% |
| CRNX Crinetics Pharmaceuticals Inc. | 8.55% | 4,288,120 | $143.8M | No change |
| PRTA Prothena Corp. PLC | 8.53% | 11,584,280 | $143.4M | No change |
| SRPT Sarepta Therapeutics Inc. | 4.91% | 1,292,386 | $82.5M | Add +67.8% |
| XNCR Xencor Inc. | 3.89% | 6,144,767 | $65.4M | No change |
| CRSP Crispr Therapeutics AG | 2.81% | 1,389,276 | $47.3M | No change |
| QURE Uniqure NV | 2.51% | 3,988,971 | $42.3M | Add +17.3% |
| JANX Janux Therapeutics Inc. | 2.36% | 1,469,818 | $39.7M | No change |
| IMNM Immunome Inc. | 1.63% | 4,079,415 | $27.5M | Add +5.2% |
| ETON Eton Pharmaceuticals Inc. | 1.50% | 1,939,288 | $25.2M | Add +6.0% |
| MDGL Madrigal Pharmaceuticals Inc. | 1.48% | 75,000 | $24.8M | No change |
| ORIC Oric Pharmaceuticals Inc. | 1.13% | 3,418,068 | $19.1M | No change |
| AKRO Akero Therapeutics Inc. | 1.06% | 440,000 | $17.8M | New |
| KURA Kura Oncology Inc. | 1.04% | 2,640,298 | $17.4M | Reduce -25.8% |
| TECX Tectonic Therapeutic Inc. | 0.98% | 935,121 | $16.6M | Add +10.1% |
| RNAM Avidity Biosciences Inc. | 0.98% | 557,576 | $16.5M | No change |
| NGNE Neurogene Inc. | 0.89% | 1,271,342 | $14.9M | No change |
| TNGX Tango Therapeutics Inc. | 0.87% | 10,630,736 | $14.6M | No change |
| VYGR Voyager Therapeutics Inc. | 0.79% | 3,917,546 | $13.2M | No change |
| BEAM Beam Therapeutics Inc. | 0.61% | 526,685 | $10.3M | New |
| MBX MBX Biosciences Inc. | 0.55% | 1,259,273 | $9.3M | No change |
| DNA Ginkgo Bioworks Holdings Inc. | 0.50% | 1,462,328 | $8.3M | Reduce -16.1% |
| REPL Replimune Group Inc. | 0.49% | 850,341 | $8.3M | No change |
| BCYC Bicycle Therapeutics PLC-ADR | 0.46% | 910,000 | $7.7M | No change |
| DAWN Day One Biopharmaceuticals I | 0.41% | 862,068 | $6.8M | No change |
| VERV Verve Therapeutics Inc. | 0.34% | 1,250,000 | $5.7M | No change |
| ADAPY Adaptimmune Therapeutics-ADR | 0.32% | 27,404,070 | $5.4M | No change |
| LKFT Lakefront Biotherapeutic-ADR filed as GALAPAGOS NV | 0.23% | 155,006 | $3.9M | No change |
| WHWK Whitehawk Therapeutics Inc. | 0.22% | 2,082,000 | $3.7M | Add +503.0% |
| ATRA Atara Biotherapeutics Inc. | 0.20% | 573,183 | $3.4M | Add +7.7% |
| SLDB Solid Biosciences Inc. | 0.16% | 744,450 | $2.8M | New |
| KROS Keros Therapeutics Inc. | 0.11% | 187,500 | $1.9M | No change |
| RLAY Relay Therapeutics Inc. | 0.10% | 641,426 | $1.7M | No change |
| KLRS Kalaris Therapeutics Inc. | 0.10% | 201,718 | $1.6M | New |
| PRME Prime Medicine Inc. | 0.08% | 700,000 | $1.4M | No change |
| MTSR Metsera Inc. | 0.08% | 50,000 | $1.4M | New |
| TCRX Tscan Therapeutics Inc. | 0.05% | 662,833 | $915K | Reduce -86.7% |
| ALGS Aligos Therapeutics Inc. | 0.04% | 88,569 | $731K | Reduce -65.3% |
| UPB Upstream Bio Inc. | 0.02% | 60,000 | $367K | No change |
Options reported separately and not counted above: QURE calls ($1.4M), ETON calls ($655K).
Other holdings (2): bonds, preferreds, convertibles and warrants · $2.5M (not counted above)
Total filed on the 13F, all lines: $1.7B.
Portfolio Sells Q4 2024 → Q1 2025
| ARVN Arvinas Inc. | Sold out | 0.00% | −5.16 |
| SWTX Springworks Therapeutics Inc. | Sold out | 0.00% | −2.25 |
| THRD Third Harmonic Bio Inc. | Sold out | 0.00% | −1.31 |
| NMRA Neumora Therapeutics Inc. | Sold out | 0.00% | −0.88 |
| CRGX Cargo Therapeutics Inc. | Sold out | 0.00% | −0.85 |
| MLTX Moonlake Immunotherapeutics | Sold out | 0.00% | −0.72 |
| MERSANA THERAPEUTICS INC | Sold out | 0.00% | −0.65 |
| KYMR Kymera Therapeutics Inc. | Sold out | 0.00% | −0.56 |
| TCRX Tscan Therapeutics Inc. | Reduce -86.7% | 0.05% | −0.55 |
| DYN Dyne Therapeutics Inc. | Sold out | 0.00% | −0.52 |
| AVIR Atea Pharmaceuticals Inc. | Sold out | 0.00% | −0.45 |
| ALGS Aligos Therapeutics Inc. | Reduce -65.3% | 0.04% | −0.36 |
| KURA Kura Oncology Inc. | Reduce -25.8% | 1.04% | −0.20 |
| FATE Fate Therapeutics Inc. | Sold out | 0.00% | −0.20 |
| DNA Ginkgo Bioworks Holdings Inc. | Reduce -16.1% | 0.50% | −0.19 |
| ALLOVIR INC | Sold out | 0.00% | −0.16 |
| DSGN Design Therapeutics Inc. | Sold out | 0.00% | −0.11 |
| GBIO Generation Bio Co. | Sold out | 0.00% | −0.09 |
| HOOK Hookipa Pharma Inc. | Sold out | 0.00% | −0.03 |
| ARTV Artiva Biotherapeutics Inc. | Sold out | 0.00% | −0.02 |
Portfolio Buys Q4 2024 → Q1 2025
| ANAB Anaptysbio Inc. | Add +0.1% | 8.71% | +4.54 |
| ZYME Zymeworks Inc. | Add +14.8% | 12.23% | +3.42 |
| SRPT Sarepta Therapeutics Inc. | Add +67.8% | 4.91% | +1.16 |
| AKRO Akero Therapeutics Inc. | New | 1.06% | +1.06 |
| BEAM Beam Therapeutics Inc. | New | 0.61% | +0.61 |
| ETON Eton Pharmaceuticals Inc. | Add +6.0% | 1.50% | +0.52 |
| APLS Apellis Pharmaceuticals Inc. | Add +0.0% | 15.47% | +0.29 |
| WHWK Whitehawk Therapeutics Inc. | Add +503.0% | 0.22% | +0.18 |
| SLDB Solid Biosciences Inc. | New | 0.16% | +0.16 |
| QURE Uniqure NV | Add +17.3% | 2.51% | +0.11 |
| KLRS Kalaris Therapeutics Inc. | New | 0.10% | +0.10 |
| MTSR Metsera Inc. | New | 0.08% | +0.08 |
| IMNM Immunome Inc. | Add +5.2% | 1.63% | −0.02 |
| ATRA Atara Biotherapeutics Inc. | Add +7.7% | 0.20% | −0.08 |
| TECX Tectonic Therapeutic Inc. | Add +10.1% | 0.98% | −0.58 |
Options Activity Q4 2024 → Q1 2025
| PFE Pfizer Inc. | call | Sold out | 5,000,000 | $132.7Mbefore exit |
| QURE Uniqure NV | call | Reduce -64.9% | 135,000 | $1.4M |
| ETON Eton Pharmaceuticals Inc. | call | Reduce -66.6% | 50,500 | $655K |
| GLUE Monte Rosa Therapeutics Inc. | call | Sold out | 21,700 | $151Kbefore exit |
Calls and puts are listed by the shares they cover; their value is not part of the stock holdings above.
All Filings
| Quarter | Positions | 13F Reported Value | Top Holdings |
|---|---|---|---|
| Q2 2026 | 30 | $2.0B | ZYME, ANAB, AKTS, CGON, ETON |
| Q1 2026 | 28 | $2.3B | ZYME, ANAB, JAZZ, CNTA, CRNX |
| Q4 2025 | 26 | $2.2B | ZYME, ANAB, JAZZ, CRNX, CNTA |
| Q3 2025 | 28 | $2.1B | ZYME, ANAB, QURE, JAZZ, CRNX |
| Q2 2025 | 34 | $1.7B | ZYME, APLS, JAZZ, ANAB, CRNX |
| Q1 2025 | 42 | $1.7B | APLS, JAZZ, ZYME, ANAB, CRNX |
| Q4 2024 | 53 | $2.5B | APLS, ZYME, CRNX, JAZZ, PRTA |
| Q3 2024 | 60 | $2.9B | APLS, ANAB, CRNX, PRTA, JAZZ |
| Q2 2024 | 52 | $3.3B | APLS, PRTA, SRPT, ANAB, CRNX |
| Q1 2024 | 54 | $3.9B | APLS, PRTA, ARVN, SRPT, CRNX |