EcoR1 Capital, LLC — 13F Holdings & Portfolio
CIK 1587114 · latest 13F-HR filed 2026-08-14
EcoR1 Capital, LLC manages $2.06B in 13F-reported U.S. long-equity assets across 33 reported positions as of its 2026-06-30 13F-HR filing. Its largest disclosed positions are ZYME (29.19%), ANAB (25.86%), AKTS (7.56%). Quarter over quarter (versus its 2026-03-31 filing) the fund opened 9 new positions and exited 7; 10 existing positions rose in reported value and 7 fell.
AUM is the long-equity portion reported on Form 13F-HR. Excludes short positions, cash, foreign holdings, and non-13F assets. For informational purposes only — not investment advice.
Long-equity book
Distinct positions
Filed 2026-08-14
vs 2026-03-31
Portfolio charts
Latest quarter's book, what changed, and how the portfolio has evolved across filings.
| Name | Title / Status | Ownership | Type |
|---|
Quarter-over-quarter changes
Changes in reported position value vs the prior 13F, so price moves count too, not just shares bought or sold.
Top Adds (vs prior quarter)
- ANAPTYSBIO INC$94.9M +21.7%
- AKTIS ONCOLOGY INC$69.2M +80.2%
- CG ONCOLOGY INC$31.6M +42.4%
- ETON PHARMACEUTICALS INC$25.0M +46.7%
- STOKE THERAPEUTICS INC$20.8M +638.6%
Top Trims
- ORIC PHARMACEUTICALS INC-$12.4M -14.5%
- ERASCA INC-$8.5M -58.5%
- RELAY THERAPEUTICS INC-$5.9M -31.1%
- MEREO BIOPHARMA GROUP PLC-$4.1M -92.8%
- BRIDGEBIO ONCOLOGY THERAPEUT-$3.8M -14.9%
New Positions
- FIRST TRACKS BIOTHERAPEUTICS$63.9M
- FULCRUM THERAPEUTICS INC$24.0M
- LEGEND BIOTECH CORP$23.1M
- AURA BIOSCIENCES INC$11.8M
- ODYSSEY THERAPEUTICS INC$10.4M
Exited Positions
- JAZZ PHARMACEUTICALS PLC$322.6M
- CENTESSA PHARMACEUTICALS PLC$238.3M
- CRINETICS PHARMACEUTICALS IN$155.7M
- XENCOR INC$26.3M
- REPLIMUNE GROUP INC$7.7M
EcoR1 Capital, LLC Holdings (2026-06-30)
Rows tagged Call or Put are options positions, not stock. Per SEC Form 13F-HR, Value shows the notional value of the underlying (shares covered × underlying price), not the option premium. Shares is the number of underlying shares covered (divide by 100 for contract count).
| # | Issuer | Symbol | CUSIP | Value | Weight | Shares | Type |
|---|---|---|---|---|---|---|---|
| 1 | ZYMEWORKS INC | ZYME | 98985Y108 | $600.4M | 29.19% | 22,970,388 | SH |
| 2 | ANAPTYSBIO INC | ANAB | 032724106 | $531.9M | 25.86% | 7,880,094 | SH |
| 3 | AKTIS ONCOLOGY INC | AKTS | 01021M104 | $155.5M | 7.56% | 4,824,469 | SH |
| 4 | CG ONCOLOGY INC | CGON | 156944100 | $106.2M | 5.16% | 1,494,300 | SH |
| 5 | ETON PHARMACEUTICALS INC | ETON | 29772L108 | $78.6M | 3.82% | 2,171,938 | SH |
| 6 | CRISPR THERAPEUTICS AG | CRSP | H17182108 | $75.8M | 3.68% | 1,389,276 | SH |
| 7 | ORIC PHARMACEUTICALS INC | ORIC | 68622P109 | $72.9M | 3.54% | 6,728,116 | SH |
| 8 | FIRST TRACKS BIOTHERAPEUTICS | TRAX | 337185102 | $63.9M | 3.11% | 3,174,519 | SH |
| 9 | LAKEFRONT BIOTHERAPEUTICS NV | LKFT | 36315X101 | $50.0M | 2.43% | 1,667,119 | SH |
| 10 | NEUROGENE INC | NGNE | 64135M105 | $40.0M | 1.94% | 1,271,342 | SH |
| 11 | CG ONCOLOGY INC Call | CGON | 156944100 | $39.9M | 1.94% | 561,500 | SH |
| 12 | STOKE THERAPEUTICS INC | STOK | 86150R107 | $24.0M | 1.17% | 735,000 | SH |
| 13 | FULCRUM THERAPEUTICS INC | FULC | 359616109 | $24.0M | 1.17% | 6,549,866 | SH |
| 14 | LEGEND BIOTECH CORP | LEGN | 52490G102 | $23.1M | 1.12% | 800,000 | SH |
| 15 | BRIDGEBIO ONCOLOGY THERAPEUT | BBOT | 107924102 | $21.5M | 1.05% | 2,823,126 | SH |
| 16 | MBX BIOSCIENCES INC | MBX | 55287L101 | $21.4M | 1.04% | 388,500 | SH |
| 17 | ZENAS BIOPHARMA INC | ZBIO | 98937L105 | $20.0M | 0.97% | 789,500 | SH |
| 18 | ATARA BIOTHERAPEUTICS INC | ATRA | 046513206 | $17.8M | 0.87% | 1,552,000 | SH |
| 19 | RELAY THERAPEUTICS INC | RLAY | 75943R102 | $13.1M | 0.63% | 697,948 | SH |
| 20 | AURA BIOSCIENCES INC | AURA | 05153U107 | $11.8M | 0.58% | 1,666,667 | SH |
| 21 | ODYSSEY THERAPEUTICS INC | ODTX | 67613T104 | $10.4M | 0.51% | 555,555 | SH |
| 22 | EIKON THERAPEUTICS INC | EIKN | 282564103 | $9.6M | 0.46% | 732,606 | SH |
| 23 | PHARVARIS N V | PHVS | N69605108 | $8.1M | 0.40% | 235,000 | SH |
| 24 | ZURA BIO LTD | ZURA | G9TY5A101 | $7.0M | 0.34% | 1,179,715 | SH |
| 25 | PHATHOM PHARMACEUTICALS INC | PHAT | 71722W107 | $6.8M | 0.33% | 625,000 | SH |
| 26 | NURIX THERAPEUTICS INC | NRIX | 67080M103 | $6.6M | 0.32% | 270,000 | SH |
| 27 | ERASCA INC | ERAS | 29479A108 | $6.0M | 0.29% | 330,000 | SH |
| 28 | ELOXX PHARMACEUTICALS INC | ELOX | 29014R301 | $5.6M | 0.27% | 400,000 | SH |
| 29 | AARDVARK THERAPEUTICS INC | AARD | 002942100 | $2.3M | 0.11% | 396,194 | SH |
| 30 | HELIX ACQUISITION CORP III USD | HLXC | G4444S107 | $2.1M | 0.10% | 200,000 | SH |
| 31 | MEREO BIOPHARMA GROUP PLC | MREO | 589492107 | $317.7K | 0.02% | 1,000,000 | SH |
| 32 | SURROZEN INC | SRZN | 86889P117 | $115.3K | 0.01% | 4,444 | SH |
| 33 | AARDVARK THERAPEUTICS INC Call | AARD | 002942100 | $84.7K | 0.00% | 14,700 | SH |
| Period | Filed | AUM | Holdings | Accession |
|---|---|---|---|---|
| 2026-06-30 | 2026-08-14 | $2.06B | 33 | 0000935836-26-000415 |
| 2026-03-31 | 2026-05-15 | $2.36B | 30 | 0000935836-26-000270 |
| 2025-12-31 | 2026-02-17 | $2.20B | 30 | 0000935836-26-000101 |
| 2025-09-30 | 2025-11-14 | $2.08B | 30 | 0000935836-25-000671 |
SAN FRANCISCO, CA 94103