# EcoR1 Capital, LLC

> Institutional holdings reported to the SEC as of Q2 2026 on Form 13F. CIK 1587114. Source: https://holderbook.com/funds/1587114-ecor1-capital-llc/

- Reported value: $2.1B
- Positions: 31
- Weight of the ten largest: 88.2%
- Filed: 2026-08-14

A 13F reports long US equity positions only. Short positions, bonds, foreign listings, private holdings and cash are not visible, so this is not the manager's whole book.

## Holdings

| Security | Ticker | Value | Shares | Weight | Quarters held |
|---|---|---|---|---|---|
| ZYMEWORKS INC | [ZYME](https://holderbook.com/stocks/ZYME/) | $600.4M | 22,970,388 | 29.2% | 15 |
| ANAPTYSBIO INC | [ANAB](https://holderbook.com/stocks/ANAB/) | $531.9M | 7,880,094 | 25.9% | 27 |
| AKTIS ONCOLOGY INC | [AKTS](https://holderbook.com/stocks/AKTS/) | $155.5M | 4,824,469 | 7.6% | 2 |
| CG ONCOLOGY INC | [CGON](https://holderbook.com/stocks/CGON/) | $146.1M | 1,494,300 | 7.1% | 3 |
| ETON PHARMACEUTICALS INC | [ETON](https://holderbook.com/stocks/ETON/) | $78.6M | 2,171,938 | 3.8% | 8 |
| CRISPR THERAPEUTICS AG | [CRSP](https://holderbook.com/stocks/CRSP/) | $75.8M | 1,389,276 | 3.7% | 10 |
| ORIC PHARMACEUTICALS INC | [ORIC](https://holderbook.com/stocks/ORIC/) | $72.9M | 6,728,116 | 3.5% | 25 |
| FIRST TRACKS BIOTHERAPEUTICS | [TRAX](https://holderbook.com/stocks/TRAX/) | $63.9M | 3,174,519 | 3.1% | 1 |
| LAKEFRONT BIOTHERAPEUTICS NV | [LKFT](https://holderbook.com/stocks/LKFT/) | $50.0M | 1,667,119 | 2.4% | 20 |
| NEUROGENE INC | [NGNE](https://holderbook.com/stocks/NGNE/) | $40.0M | 1,271,342 | 1.9% | 11 |
| STOKE THERAPEUTICS INC | [STOK](https://holderbook.com/stocks/STOK/) | $24.0M | 735,000 | 1.2% | 2 |
| FULCRUM THERAPEUTICS INC | [FULC](https://holderbook.com/stocks/FULC/) | $24.0M | 6,549,866 | 1.2% | 1 |
| LEGEND BIOTECH CORP | [LEGN](https://holderbook.com/stocks/LEGN/) | $23.1M | 800,000 | 1.1% | 1 |
| BRIDGEBIO ONCOLOGY THERAPEUT | [BBOT](https://holderbook.com/stocks/BBOT/) | $21.5M | 2,823,126 | 1.0% | 4 |
| MBX BIOSCIENCES INC | [MBX](https://holderbook.com/stocks/MBX/) | $21.4M | 388,500 | 1.0% | 8 |
| ZENAS BIOPHARMA INC | [ZBIO](https://holderbook.com/stocks/ZBIO/) | $20.0M | 789,500 | 1.0% | 3 |
| ATARA BIOTHERAPEUTICS INC | [ATRA](https://holderbook.com/stocks/ATRA/) | $17.8M | 1,552,000 | 0.9% | 9 |
| RELAY THERAPEUTICS INC | [RLAY](https://holderbook.com/stocks/RLAY/) | $13.1M | 697,948 | 0.6% | 2 |
| AURA BIOSCIENCES INC | [AURA](https://holderbook.com/stocks/AURA/) | $11.8M | 1,666,667 | 0.6% | 1 |
| ODYSSEY THERAPEUTICS INC | [ODTX](https://holderbook.com/stocks/ODTX/) | $10.4M | 555,555 | 0.5% | 1 |
| EIKON THERAPEUTICS INC | [EIKN](https://holderbook.com/stocks/EIKN/) | $9.6M | 732,606 | 0.5% | 2 |
| PHARVARIS N V | [PHVS](https://holderbook.com/stocks/PHVS/) | $8.1M | 235,000 | 0.4% | 1 |
| ZURA BIO LTD | [ZURA](https://holderbook.com/stocks/ZURA/) | $7.0M | 1,179,715 | 0.3% | 2 |
| PHATHOM PHARMACEUTICALS INC | [PHAT](https://holderbook.com/stocks/PHAT/) | $6.8M | 625,000 | 0.3% | 2 |
| NURIX THERAPEUTICS INC | [NRIX](https://holderbook.com/stocks/NRIX/) | $6.6M | 270,000 | 0.3% | 1 |
| ERASCA INC | [ERAS](https://holderbook.com/stocks/ERAS/) | $6.0M | 330,000 | 0.3% | 2 |
| ELOXX PHARMACEUTICALS INC | - | $5.6M | 400,000 | 0.3% | 1 |
| AARDVARK THERAPEUTICS INC | [AARD](https://holderbook.com/stocks/AARD/) | $2.4M | 396,194 | 0.1% | 1 |
| HELIX ACQUISITION CORP III | [HLXC](https://holderbook.com/stocks/HLXC/) | $2.1M | 200,000 | 0.1% | 2 |
| MEREO BIOPHARMA GROUP PLC | [MREO](https://holderbook.com/stocks/MREO/) | $317.7K | 1,000,000 | 0.0% | 3 |
| SURROZEN INC | [SRZNW](https://holderbook.com/stocks/SRZNW/) | $115.3K | 4,444 | 0.0% | 20 |

## What the disclosed book did

Not the fund's return. This is the change in value of the positions disclosed on Form 13F, had they been left untouched, against SPY over the same quarter ends.

| Quarter | Book | Market | Difference | Priced |
|---|---|---|---|---|
| Q2 2026 | +18.0% | +14.8% | +3.2% | 89% |
| Q1 2026 | +2.5% | -4.6% | +7.1% | 99% |
| Q4 2025 | +19.0% | +2.4% | +16.6% | 99% |
| Q3 2025 | +43.1% | +7.8% | +35.3% | 93% |
| Q2 2025 | -5.5% | +10.5% | -16.0% | 100% |
| Q1 2025 | -29.0% | -4.6% | -24.5% | 100% |
| Q4 2024 | -13.4% | +2.1% | -15.6% | 100% |
| Q3 2024 | +0.6% | +5.4% | -4.9% | 95% |

## Quarter by quarter

| Quarter | Value | Positions |
|---|---|---|
| Q2 2026 | $2.1B | 31 |
| Q1 2026 | $2.4B | 29 |
| Q4 2025 | $2.2B | 28 |
| Q3 2025 | $2.1B | 30 |
| Q2 2025 | $1.7B | 36 |
| Q1 2025 | $1.7B | 44 |
| Q4 2024 | $2.6B | 57 |
| Q3 2024 | $2.9B | 63 |
| Q2 2024 | $3.3B | 55 |
| Q1 2024 | $4.0B | 57 |
| Q4 2023 | $3.9B | 51 |
| Q3 2023 | $3.0B | 49 |