EcoR1 Capital, LLC — 13F Holdings & Portfolio
CIK 1587114 · latest 13F-HR filed 2026-05-15
EcoR1 Capital, LLC manages $2.36B in 13F-reported U.S. long-equity assets across 30 reported positions as of its 2026-03-31 13F-HR filing. Its largest disclosed positions are ZYME (24.41%), ANAB (18.55%), JAZZ (13.69%). Quarter over quarter (versus its 2025-12-31 filing) the fund opened 10 new positions, exited 9, added to 8, and trimmed 9.
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.
$2.36B
Long-equity book
30
Distinct positions
2026-03-31
Filed 2026-05-15
+10 / −9 / ↑8 / ↓9
vs 2025-12-31
| Name | Title / Status | Ownership | Type |
|---|
Top Adds (vs prior quarter)
- CENTESSA PHARMACEUTICALS PLC$160.4M +205.9%
- ANAPTYSBIO INC$55.0M +14.4%
- CG ONCOLOGY INC$42.5M +132.7%
- JAZZ PHARMACEUTICALS PLC$32.5M +11.2%
- ORIC PHARMACEUTICALS INC$30.2M +54.9%
Top Trims
- CRINETICS PHARMACEUTICALS IN-$43.9M -22.0%
- MBX BIOSCIENCES INC-$43.8M -65.4%
- XENCOR INC-$23.4M -47.1%
- ZENAS BIOPHARMA INC-$13.2M -46.2%
- BRIDGEBIO ONCOLOGY THERAPEUT-$10.1M -28.5%
New Positions
- AKTIS ONCOLOGY INC$86.3M
- RELAY THERAPEUTICS INC$19.0M
- ERASCA INC$14.6M
- EIKON THERAPEUTICS INC$7.8M
- REPLIMUNE GROUP INC$7.7M
Exited Positions
- IMMUNOME INC$61.3M
- STRUCTURE THERAPEUTICS INC$23.3M
- VAXCYTE INC$20.8M
- AQUESTIVE THERAPEUTICS INC$17.0M
- VOYAGER THERAPEUTICS INC$15.7M
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 | $575.2M | 24.41% | 22,970,388 | SH |
| 2 | ANAPTYSBIO INC | ANAB | 032724106 | $437.0M | 18.55% | 7,880,094 | SH |
| 3 | JAZZ PHARMACEUTICALS PLC | JAZZ | G50871105 | $322.6M | 13.69% | 1,706,469 | SH |
| 4 | CENTESSA PHARMACEUTICALS PLC | CNTA | 152309100 | $238.3M | 10.11% | 6,000,000 | SH |
| 5 | CRINETICS PHARMACEUTICALS IN | CRNX | 22663K107 | $155.7M | 6.61% | 4,288,120 | SH |
| 6 | AKTIS ONCOLOGY INC | AKTS | 01021M104 | $86.3M | 3.66% | 4,824,469 | SH |
| 7 | ORIC PHARMACEUTICALS INC | ORIC | 68622P109 | $85.2M | 3.62% | 6,728,116 | SH |
| 8 | CG ONCOLOGY INC | CGON | 156944100 | $74.6M | 3.17% | 1,102,000 | SH |
| 9 | CRISPR THERAPEUTICS AG | CRSP | H17182108 | $66.1M | 2.80% | 1,389,276 | SH |
| 10 | ETON PHARMACEUTICALS INC | ETON | 29772L108 | $53.6M | 2.27% | 2,171,938 | SH |
| 11 | GALAPAGOS NV | GLPG | 36315X101 | $50.0M | 2.12% | 1,667,119 | SH |
| 12 | XENCOR INC | XNCR | 98401F105 | $26.3M | 1.12% | 2,183,000 | SH |
| 13 | NEUROGENE INC | NGNE | 64135M105 | $25.6M | 1.09% | 1,271,342 | SH |
| 14 | BRIDGEBIO ONCOLOGY THERAPEUT | BBOT | 107924102 | $25.3M | 1.07% | 2,823,126 | SH |
| 15 | MBX BIOSCIENCES INC | MBX | 55287L101 | $23.2M | 0.98% | 777,000 | SH |
| 16 | RELAY THERAPEUTICS INC | RLAY | 75943R102 | $19.0M | 0.80% | 1,904,762 | SH |
| 17 | CENTESSA PHARMACEUTICALS PLC Call | CNTA | 152309100 | $16.3M | 0.69% | 410,800 | SH |
| 18 | ZENAS BIOPHARMA INC | ZBIO | 98937L105 | $15.4M | 0.66% | 789,500 | SH |
| 19 | ERASCA INC | ERAS | 29479A108 | $14.6M | 0.62% | 900,000 | SH |
| 20 | EIKON THERAPEUTICS INC | EIKN | 282564103 | $7.8M | 0.33% | 732,606 | SH |
| 21 | REPLIMUNE GROUP INC | REPL | 76029N106 | $7.7M | 0.32% | 1,000,000 | SH |
| 22 | ZURA BIO LTD | ZURA | G9TY5A101 | $7.0M | 0.30% | 1,179,715 | SH |
| 23 | PHATHOM PHARMACEUTICALS INC | PHAT | 71722W107 | $6.9M | 0.29% | 625,000 | SH |
| 24 | MEREO BIOPHARMA GROUP PLC | MREO | 589492107 | $4.4M | 0.19% | 13,368,855 | SH |
| 25 | STOKE THERAPEUTICS INC | STOK | 86150R107 | $3.3M | 0.14% | 100,000 | SH |
| 26 | PRELUDE THERAPEUTICS INC | PRLD | 74065P101 | $3.2M | 0.14% | 947,049 | SH |
| 27 | IBIO INC | IBIO | 451033708 | $3.0M | 0.13% | 1,583,000 | SH |
| 28 | HELIX ACQUISITION CORP III USD | HLXC | G4444S107 | $2.0M | 0.09% | 200,000 | SH |
| 29 | ATARA BIOTHERAPEUTICS INC | ATRA | 046513206 | $471.1K | 0.02% | 99,593 | SH |
| 30 | SURROZEN INC | SRZNW | 86889P117 | $129.5K | 0.01% | 4,444 | SH |
| Period | Filed | AUM | Holdings | Accession |
|---|---|---|---|---|
| 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 |