EcoR1 Capital, LLC 13F holdings
EcoR1 Capital, LLC reported 31 positions with a total reported value of $2.0B as of 2026-06-30, in its 13F for Q2 2026, filed 2026-08-14. Top holdings by reported value: ZYME ZYMEWORKS INC (29.8%), ANAB ANAPTYSBIO INC (26.4%), AKTS AKTIS ONCOLOGY INC (7.7%), CGON CG ONCOLOGY INC (5.3%), ETON ETON PHARMACEUTICALS INC (3.9%). Against 2026-03-31 it opened 10 new positions and exited 8. Next 13F due by 2026-11-14, the legal deadline 45 days after the quarter ending 2026-09-30.
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Top holdings
25 largest of 31 positions · reported value as of 2026-06-30
| Holding | Shares | Reported value | % of portfolio |
|---|---|---|---|
| ZYME ZYMEWORKS INC | 22,970,388 | $600.4M | 29.8% |
| ANAB ANAPTYSBIO INC | 7,880,094 | $531.9M | 26.4% |
| AKTS AKTIS ONCOLOGY INC | 4,824,469 | $155.5M | 7.7% |
| CGON CG ONCOLOGY INC | 1,494,300 | $106.2M | 5.3% |
| ETON ETON PHARMACEUTICALS INC | 2,171,938 | $78.6M | 3.9% |
| CRSP CRISPR THERAPEUTICS AG | 1,389,276 | $75.8M | 3.8% |
| ORIC ORIC PHARMACEUTICALS INC | 6,728,116 | $72.9M | 3.6% |
| TRAX FIRST TRACKS BIOTHERAPEUTICS | 3,174,519 | $63.9M | 3.2% |
| LAKEFRONT BIOTHERAPEUTICS NV | 1,667,119 | $50.0M | 2.5% |
| NGNE NEUROGENE INC | 1,271,342 | $40.0M | 2.0% |
| STOK STOKE THERAPEUTICS INC | 735,000 | $24.0M | 1.2% |
| FULC FULCRUM THERAPEUTICS INC | 6,549,866 | $24.0M | 1.2% |
| LEGN LEGEND BIOTECH CORP | 800,000 | $23.1M | 1.1% |
| BBOT BRIDGEBIO ONCOLOGY THERAPEUT | 2,823,126 | $21.5M | 1.1% |
| MBX MBX BIOSCIENCES INC | 388,500 | $21.4M | 1.1% |
| ZBIO ZENAS BIOPHARMA INC | 789,500 | $20.0M | 1.0% |
| ATRA ATARA BIOTHERAPEUTICS INC | 1,552,000 | $17.8M | 0.9% |
| RLAY RELAY THERAPEUTICS INC | 697,948 | $13.1M | 0.6% |
| AURA AURA BIOSCIENCES INC | 1,666,667 | $11.8M | 0.6% |
| ODTX ODYSSEY THERAPEUTICS INC | 555,555 | $10.4M | 0.5% |
| EIKN EIKON THERAPEUTICS INC | 732,606 | $9.6M | 0.5% |
| PHVS PHARVARIS N V | 235,000 | $8.1M | 0.4% |
| ZURA ZURA BIO LTD | 1,179,715 | $7.0M | 0.3% |
| PHAT PHATHOM PHARMACEUTICALS INC | 625,000 | $6.8M | 0.3% |
| NRIX NURIX THERAPEUTICS INC | 270,000 | $6.6M | 0.3% |
SEC FORM 13F · Q2 2026 · VALUES AS REPORTED, NOT PRICES
New positions this quarter
Held at 2026-06-30, not at 2026-03-31 · 10 in all · reported value as of 2026-06-30
| Holding | Shares | Reported value | % of portfolio |
|---|---|---|---|
| TRAX FIRST TRACKS BIOTHERAPEUTICS | 3,174,519 | $63.9M | 3.2% |
| LAKEFRONT BIOTHERAPEUTICS NV | 1,667,119 | $50.0M | 2.5% |
| FULC FULCRUM THERAPEUTICS INC | 6,549,866 | $24.0M | 1.2% |
| LEGN LEGEND BIOTECH CORP | 800,000 | $23.1M | 1.1% |
| AURA AURA BIOSCIENCES INC | 1,666,667 | $11.8M | 0.6% |
| ODTX ODYSSEY THERAPEUTICS INC | 555,555 | $10.4M | 0.5% |
| PHVS PHARVARIS N V | 235,000 | $8.1M | 0.4% |
| NRIX NURIX THERAPEUTICS INC | 270,000 | $6.6M | 0.3% |
| ELOX ELOXX PHARMACEUTICALS INC | 400,000 | $5.6M | 0.3% |
| AARD AARDVARK THERAPEUTICS INC | 396,194 | $2.3M | 0.1% |
Sold out
Held at 2026-03-31, gone by 2026-06-30 · 8 in all · reported value as of 2026-03-31
| Holding | Shares 2026-03-31 | Reported value | % of portfolio then |
|---|---|---|---|
| JAZZ JAZZ PHARMACEUTICALS PLC | 1,706,469 | $322.6M | 13.8% |
| CENTESSA PHARMACEUTICALS PLC | 6,000,000 | $238.3M | 10.2% |
| CRNX CRINETICS PHARMACEUTICALS IN | 4,288,120 | $155.7M | 6.7% |
| GALAPAGOS NV | 1,667,119 | $50.0M | 2.1% |
| XNCR XENCOR INC | 2,183,000 | $26.3M | 1.1% |
| REPL REPLIMUNE GROUP INC | 1,000,000 | $7.7M | 0.3% |
| PRLD PRELUDE THERAPEUTICS INC | 947,049 | $3.2M | 0.1% |
| IBIO IBIO INC | 1,583,000 | $3.0M | 0.1% |
Biggest increases and decreases
Positions held at both quarter ends, by change in shares · reported value as of 2026-06-30
Increases
| Holding | Shares 2026-03-31 | Shares 2026-06-30 | Change | Reported value |
|---|---|---|---|---|
| CGON CG ONCOLOGY INC | 1,102,000 | 1,494,300 | +35.6% | $106.2M |
| STOK STOKE THERAPEUTICS INC | 100,000 | 735,000 | +635.0% | $24.0M |
| ATRA ATARA BIOTHERAPEUTICS INC | 99,593 | 1,552,000 | +1,458.3% | $17.8M |
Decreases
| Holding | Shares 2026-03-31 | Shares 2026-06-30 | Change | Reported value |
|---|---|---|---|---|
| RLAY RELAY THERAPEUTICS INC | 1,904,762 | 697,948 | -63.4% | $13.1M |
| MBX MBX BIOSCIENCES INC | 777,000 | 388,500 | -50.0% | $21.4M |
| ERAS ERASCA INC | 900,000 | 330,000 | -63.3% | $6.0M |
| MREO MEREO BIOPHARMA GROUP PLC | 13,368,855 | 1,000,000 | -92.5% | $317.7K |
CIK 1587114 · 13F FILINGS ON EDGAR · INFORMATIONAL ONLY
