EcoR1 Capital, LLC: 13F holdings, Q2 2026
Hedge fund · SEC EDGAR filings (CIK 1587114) · Explore on the interactive board
EcoR1 Capital, LLC disclosed 31 US equity positions worth $2.0bn in its Q2 2026 13F filing (holdings as of June 30, 2026, filed August 14, 2026). Its largest position is ZYME at 29.8% of the reported book, followed by ANAB, AKTS. The top ten holdings are 88.0% of the book, and the portfolio behaves like about 6 equal-weight positions. Versus the prior filing it opened 9 new positions, added to 3, reduced 4 and exited 7. Note: this manager's most recent filing is 3934 quarters behind the newest quarter on file, so these figures are history rather than current positioning.
What does EcoR1 Capital, LLC own? Top holdings as of June 30, 2026
Change is measured in shares against the previous filing (Q1 2026), so price moves do not read as decisions. This quarter: 9 new, 3 added, 4 reduced, 7 exited.
| # | Stock | Sector | Weight | Value | Shares | Δ shares | Action |
|---|---|---|---|---|---|---|---|
| 1 | ZYME ZYMEWORKS INC | Healthcare | 29.8% | $600.4m | 22,970,388 | 0% | held |
| 2 | ANAB ANAPTYSBIO INC | Healthcare | 26.4% | $531.9m | 7,880,094 | 0% | held |
| 3 | AKTS AKTIS ONCOLOGY INC | 7.7% | $155.5m | 4,824,469 | 0% | held | |
| 4 | CGON CG ONCOLOGY INC | Healthcare | 5.3% | $106.2m | 1,494,300 | 36% | added |
| 5 | ETON ETON PHARMACEUTICALS INC | 3.9% | $78.6m | 2,171,938 | 0% | held | |
| 6 | CRSP CRISPR THERAPEUTICS AG | Healthcare | 3.8% | $75.8m | 1,389,276 | 0% | held |
| 7 | ORIC ORIC PHARMACEUTICALS INC | Healthcare | 3.6% | $72.9m | 6,728,116 | 0% | held |
| 8 | TRAX FIRST TRACKS BIOTHERAPEUTICS | 3.2% | $63.9m | 3,174,519 | – | new | |
| 9 | LKFT LAKEFRONT BIOTHERAPEUTICS NV | Healthcare | 2.5% | $50.0m | 1,667,119 | 0% | held |
| 10 | NGNE NEUROGENE INC | 2.0% | $40.0m | 1,271,342 | 0% | held | |
| 11 | STOK STOKE THERAPEUTICS INC | Healthcare | 1.2% | $24.0m | 735,000 | 635% | added |
| 12 | FULC FULCRUM THERAPEUTICS INC | Healthcare | 1.2% | $24.0m | 6,549,866 | – | new |
| 13 | LEGN LEGEND BIOTECH CORP | Healthcare | 1.1% | $23.1m | 800,000 | – | new |
| 14 | BBOT BRIDGEBIO ONCOLOGY THERAPEUT | 1.1% | $21.5m | 2,823,126 | 0% | held | |
| 15 | MBX MBX BIOSCIENCES INC | Healthcare | 1.1% | $21.4m | 388,500 | -50% | reduced |
| 16 | ZBIO ZENAS BIOPHARMA INC | 1.0% | $20.0m | 789,500 | 0% | held | |
| 17 | ATRA ATARA BIOTHERAPEUTICS INC | 0.9% | $17.8m | 1,552,000 | 1458% | added | |
| 18 | RLAY RELAY THERAPEUTICS INC | Healthcare | 0.6% | $13.1m | 697,948 | -63% | reduced |
| 19 | AURA AURA BIOSCIENCES INC | 0.6% | $11.8m | 1,666,667 | – | new | |
| 20 | ODYSSEY THERAPEUTICS INC | 0.5% | $10.4m | 555,555 | – | new | |
| 21 | EIKN EIKON THERAPEUTICS INC | 0.5% | $9.6m | 732,606 | 0% | held | |
| 22 | PHVS PHARVARIS N V | Healthcare | 0.4% | $8.1m | 235,000 | – | new |
| 23 | ZURA ZURA BIO LTD | Healthcare | 0.3% | $7.0m | 1,179,715 | 0% | held |
| 24 | PHAT PHATHOM PHARMACEUTICALS INC | Healthcare | 0.3% | $6.8m | 625,000 | 0% | held |
| 25 | NRIX NURIX THERAPEUTICS INC | Healthcare | 0.3% | $6.6m | 270,000 | – | new |
| 26 | ERAS ERASCA INC | Healthcare | 0.3% | $6.0m | 330,000 | -63% | reduced |
| 27 | ELOXX PHARMACEUTICALS INC | 0.3% | $5.6m | 400,000 | – | new | |
| 28 | AARD AARDVARK THERAPEUTICS INC | 0.1% | $2.3m | 396,194 | – | new | |
| 29 | HELIX ACQUISITION CORP III USD | 0.1% | $2.1m | 200,000 | 0% | held | |
| 30 | MREO MEREO BIOPHARMA GROUP PLC | Healthcare | 0.0% | $317.7k | 1,000,000 | -93% | reduced |
| 31 | SURROZEN INC | 0.0% | $115.3k | 4,444 | 0% | held |
What did EcoR1 Capital, LLC sell? Positions exited since the previous filing
| Stock | Prior weight | Prior value |
|---|---|---|
| JAZZ JAZZ PHARMACEUTICALS PLC | 42.6% | $322.6m |
| CNTA CENTESSA PHARMACEUTICALS PLC | 31.5% | $238.3m |
| CRNXGBP CRINETICS PHARMACEUTICALS IN | 20.6% | $155.7m |
| XNCR XENCOR INC | 3.5% | $26.3m |
| REPL REPLIMUNE GROUP INC | 1.0% | $7.7m |
| PRLD PRELUDE THERAPEUTICS INC | 0.4% | $3.2m |
| IBIO IBIO INC | 0.4% | $3.0m |
Sector mix
| Sector | Weight |
|---|---|
| Healthcare | 78.2% |
Sectors cover positions whose ticker resolved to a sector; the remainder is unclassified, not cash.
Filing history
How concentrated is EcoR1 Capital, LLC's portfolio?
Across every quarter EcoR1 Capital, LLC has filed, its median largest position is 27.2% of the book and its median top-ten weight is 88.8%, which WhaleCreep classifies as concentrated (the gate is a median largest position of 5%). Of 7.0 completed holding spells, the median lasted 1.0 quarters; 31.0 positions are still open and their final length is unknown.