EcoR1 Capital, LLC
Long book
$2.34B
Q1 2026
Positions
29
Top-10 weight
90%
concentration
Last quarter
+30.7%
SPY +14.8%
Turnover
50%
of book per quarter
Strategy in plain words
auto-generated from filingsEcoR1 Capital, LLC is a concentrated fundamental stock-picker, specialised in healthcare (100% of the long book), running a $2.34B US long book across 29 positions.
The portfolio is extremely concentrated — the top 10 positions are almost the whole book. The portfolio is actively managed, with meaningful quarterly turnover. Current anchor positions: ZYMEWORKS INC, ANAPTYSBIO INC, JAZZ PHARMACEUTICALS PLC, CENTESSA PHARMACEUTICALS-ADR, CRINETICS PHARMACEUTICALS IN.
Over the last 9 quarters its long book ran on average 0.4pp per quarter behind the S&P 500, beating the index in 4 of 9 quarters. We rate its filings as signal-bearing: position changes reflect genuine views.
Implied long-book return vs S&P 500
methodology: positions priced quarterly, no shorts/options Fund long book S&P 500
Q1 2024
-14.5%
Q2 2024
+4.1%
Q3 2024
-16.3%
Q4 2024
-28.8%
Q1 2025
-3.7%
Q2 2025
+46.3%
Q3 2025
+18.6%
Q4 2025
+0.4%
Q1 2026
+30.7%
Sector allocation
Healthcare 100%
Financials 0%
Long book by quarter
What does EcoR1 Capital, own?
Q1 2026 13F| Company | Sector | Shares | Value | % of book | Change |
|---|---|---|---|---|---|
| ZYME ZYMEWORKS INC | Healthcare | 23.0M | $575.2M | 24.6% | Held |
| ANAB ANAPTYSBIO INC | Healthcare | 7.9M | $437.0M | 18.7% | Held |
| JAZZ JAZZ PHARMACEUTICALS PLC | Healthcare | 1.7M | $322.6M | 13.8% | Held |
| CRNX CRINETICS PHARMACEUTICALS IN | Healthcare | 4.3M | $155.7M | 6.7% | Held |
| AKTS AKTIS ONCOLOGY INC | Healthcare | 4.8M | $86.3M | 3.7% | New |
| ORIC ORIC PHARMACEUTICALS INC | Healthcare | 6.7M | $85.2M | 3.6% | Held |
| CGON CG ONCOLOGY INC | Healthcare | 1.1M | $74.6M | 3.2% | +42.7% |
| CRSP CRISPR THERAPEUTICS AG | Healthcare | 1.4M | $66.1M | 2.8% | Held |
| ETON ETON PHARMACEUTICALS INC | Healthcare | 2.2M | $53.6M | 2.3% | +7.0% |
| XNCR XENCOR INC | Healthcare | 2.2M | $26.3M | 1.1% | -32.9% |
| NGNE NEUROGENE INC | Healthcare | 1.3M | $25.6M | 1.1% | Held |
| BBOT BRIDGEBIO ONCOLOGY THERAPEUT | Healthcare | 2.8M | $25.3M | 1.1% | Held |
| MBX MBX BIOSCIENCES INC | Healthcare | 777.0K | $23.2M | 1.0% | -63.4% |
| RLAY RELAY THERAPEUTICS INC | Healthcare | 1.9M | $19.0M | 0.8% | New |
| ZBIO ZENAS BIOPHARMA INC | Healthcare | 789.5K | $15.4M | 0.7% | Held |
| ERAS ERASCA INC | Healthcare | 900.0K | $14.6M | 0.6% | New |
| EIKN EIKON THERAPEUTICS INC | Healthcare | 732.6K | $7.8M | 0.3% | New |
| REPL REPLIMUNE GROUP INC | Healthcare | 1.0M | $7.7M | 0.3% | New |
| ZURA ZURA BIO LTD | Healthcare | 1.2M | $7.0M | 0.3% | New |
| PHAT PHATHOM PHARMACEUTICALS INC | Healthcare | 625.0K | $6.9M | 0.3% | New |
| STOK STOKE THERAPEUTICS INC | Healthcare | 100.0K | $3.3M | 0.1% | New |
| PRLD PRELUDE THERAPEUTICS INC | Healthcare | 947.0K | $3.2M | 0.1% | New |
| IBIO IBIO INC | Healthcare | 1.6M | $3.0M | 0.1% | -28.9% |
| HLXC HELIX ACQUISITION CORP-CL A | Financials | 200.0K | $2.0M | 0.1% | New |
| ATRA ATARA BIOTHERAPEUTICS INC | Healthcare | 99.6K | $471K | 0.0% | -82.6% |
13F filing history
| Period | Form | Filed | Entries | Reported value | Flags | Source |
|---|---|---|---|---|---|---|
| Q1 2026 | 13F-HR | May 15, 2026 | 30 | $2.36B | canonical | SEC ↗ |
| Q4 2025 | 13F-HR | Feb 17, 2026 | 30 | $2.20B | canonical | SEC ↗ |
| Q3 2025 | 13F-HR | Nov 14, 2025 | 30 | $2.08B | canonical | SEC ↗ |
| Q2 2025 | 13F-HR | Aug 14, 2025 | 37 | $1.69B | canonical | SEC ↗ |
| Q1 2025 | 13F-HR | May 15, 2025 | 46 | $1.69B | canonical | SEC ↗ |
| Q4 2024 | 13F-HR | Feb 14, 2025 | 59 | $2.65B | canonical | SEC ↗ |
| Q3 2024 | 13F-HR | Nov 14, 2024 | 64 | $2.92B | canonical | SEC ↗ |
| Q2 2024 | 13F-HR | Aug 14, 2024 | 55 | $3.27B | canonical | SEC ↗ |
| Q1 2024 | 13F-HR | May 15, 2024 | 59 | $3.95B | canonical | SEC ↗ |