EcoR1 Capital
San Francisco, CAfiles as EcoR1 Capital, LLC
$2.0bn in 31 US stocks at the end of 30 June 2026. The top 10 are 88.0% of the money. It changed about 33.0% of the portfolio this quarter.
Value
$2.0bn
Stocks
31
Top 10 share
88.0%
Turnover
33.0%
What changed this quarter
New
Bought for the first time this quarter.
- First Tracks BiotherapeuticsTRAX3.2% of the fund
- Fulcrum TherapeuticsFULC1.2% of the fund
- Legend BiotechLEGN1.1% of the fund
- Aura BiosciencesAURA0.6% of the fund
- Odyssey TherapeuticsODTX0.5% of the fund
- PharvarisPHVS0.4% of the fund
- Nurix TherapeuticsNRIX0.3% of the fund
- Eloxx PharmaceuticalsELOX0.3% of the fund
- Aardvark TherapeuticsAARD0.1% of the fund
Added
Bought more of a stock they already held.
- CG OncologyCGON5.3% of the fund+36%
- Stoke TherapeuticsSTOK1.2% of the fund+635%
- Atara BiotherapeuticsATRA0.9% of the fund+1458%
Cut
Sold some of their stake.
- MBX BiosciencesMBX1.1% of the fund-50%
- Relay TherapeuticsRLAY0.6% of the fund-63%
- ErascaERAS0.3% of the fund-63%
- Mereo Biopharma GroupMREO<0.1% of the fund-93%
Sold out
Sold their entire stake.
- Jazz PharmaceuticalsJAZZ-100%
- Centessa Pharmaceuticals-100%
- Crinetics PharmaceuticalsCRNX-100%
- XencorXNCR-100%
- Replimune GroupREPL-100%
- Prelude TherapeuticsPRLD-100%
- iBioIBIO-100%
Holdings
- First Tracks BiotherapeuticsTRAX
- Share
- 3.2%
- Value
- $64m
- Shares
- 3,174,519
New
- Lakefront Biotherapeutics NVLKFT
- Share
- 2.5%
- Value
- $50m
- Shares
- 1,667,119
Held
- Legend BiotechLEGN
- Share
- 1.1%
- Value
- $23m
- Shares
- 800,000
New
- Odyssey TherapeuticsODTX
- Share
- 0.5%
- Value
- $10m
- Shares
- 555,555
New
- Helix Acquisition Corp. IIIHLXC
- Share
- 0.1%
- Value
- $2m
- Shares
- 200,000
Held
- Mereo Biopharma GroupMREO
- Share
- <0.1%
- Value
- $317,700
- Shares
- 1,000,000
-93%
- Surrozen
- Share
- <0.1%
- Value
- $115,322
- Shares
- 4,444
Held
| Company | Share of fund | Value | Shares | Change |
|---|---|---|---|---|
| ZymeworksZYME | 29.8% | $600m | 22,970,388 | Held |
| AnaptysbioANAB | 26.4% | $532m | 7,880,094 | Held |
| Aktis OncologyAKTS | 7.7% | $155m | 4,824,469 | Held |
| CG OncologyCGON | 5.3% | $106m | 1,494,300 | +36% |
| Eton PharmaceuticalsETON | 3.9% | $79m | 2,171,938 | Held |
| CRISPR Therapeutics AGCRSP | 3.8% | $76m | 1,389,276 | Held |
| Oric PharmaceuticalsORIC | 3.6% | $73m | 6,728,116 | Held |
| First Tracks BiotherapeuticsTRAX | 3.2% | $64m | 3,174,519 | New |
| Lakefront Biotherapeutics NVLKFT | 2.5% | $50m | 1,667,119 | Held |
| NeurogeneNGNE | 2.0% | $40m | 1,271,342 | Held |
| Stoke TherapeuticsSTOK | 1.2% | $24m | 735,000 | +635% |
| Fulcrum TherapeuticsFULC | 1.2% | $24m | 6,549,866 | New |
| Legend BiotechLEGN | 1.1% | $23m | 800,000 | New |
| BridgeBio Oncology TherapeuticsBBOT | 1.1% | $22m | 2,823,126 | Held |
| MBX BiosciencesMBX | 1.1% | $21m | 388,500 | -50% |
| Zenas BioPharmaZBIO | 1.0% | $20m | 789,500 | Held |
| Atara BiotherapeuticsATRA | 0.9% | $18m | 1,552,000 | +1458% |
| Relay TherapeuticsRLAY | 0.6% | $13m | 697,948 | -63% |
| Aura BiosciencesAURA | 0.6% | $12m | 1,666,667 | New |
| Odyssey TherapeuticsODTX | 0.5% | $10m | 555,555 | New |
| Eikon TherapeuticsEIKN | 0.5% | $10m | 732,606 | Held |
| PharvarisPHVS | 0.4% | $8m | 235,000 | New |
| Zura BioZURA | 0.3% | $7m | 1,179,715 | Held |
| Phathom PharmaceuticalsPHAT | 0.3% | $7m | 625,000 | Held |
| Nurix TherapeuticsNRIX | 0.3% | $7m | 270,000 | New |
| ErascaERAS | 0.3% | $6m | 330,000 | -63% |
| Eloxx PharmaceuticalsELOX | 0.3% | $6m | 400,000 | New |
| Aardvark TherapeuticsAARD | 0.1% | $2m | 396,194 | New |
| Helix Acquisition Corp. IIIHLXC | 0.1% | $2m | 200,000 | Held |
| Mereo Biopharma GroupMREO | <0.1% | $317,700 | 1,000,000 | -93% |
| Surrozen | <0.1% | $115,322 | 4,444 | Held |
Options (2)
- CG OncologyCGON
- Type
- Call
- Value
- $40m
- Contracts
- 561,500
- Aardvark TherapeuticsAARD
- Type
- Call
- Value
- $84,672
- Contracts
- 14,700
| Company | Type | Value | Contracts |
|---|---|---|---|
| CG OncologyCGON | Call | $40m | 561,500 |
| Aardvark TherapeuticsAARD | Call | $84,672 | 14,700 |
Over time and by industry
Value over time
Jun '25
Dec '25
Jun '26
Value is up 19.5% since 30 June 2025.
Where the money is
Health care96.2%
Financial services0.1%
Other3.6%
From the fund's 13F filings. They list US stocks and options only, 45 days after each quarter, and leave out cash, bonds, shorts and foreign shares.