EC
EcoR1 Capital, LLC — 13F Filing & Top Stock Positions (Q2 2026)
EcoR1 Capital, LLCCIK: 0001587114
Sector-focusedMomentum followerQuality / disciplined sizing
Total reported value
$2.1B
Reporting period: 2026-06-30 · Number of holdings: 33
EcoR1 Capital, LLC disclosed 33 holdings in its latest 13F filing for the period ending 2026-06-30, with total reported value of $2.1B and a quarterly turnover rate of 59.8%.
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Personality snowflake
- Concentration
- 67.94
- Portfolio Stability
- 59.83
- Momentum
- 100
- Sector conviction
- 100
- Diversification
- 62
- Sizing Uniformity
- 79.01
EcoR1 Capital, LLC's disclosed holdings carry a Herfindahl concentration index of 0.170 — mathematically equivalent to about 6 equally-sized positions, well below its 33 actual disclosed holdings. That gap points to a strategy built around a small core of high-conviction bets rather than broad diversification.
Position sizes vary widely across the portfolio (a coefficient of variation of 2.10), with a handful of outsized bets alongside many smaller positions.
No strong tilt toward either adding to existing winners or initiating outsized new positions was observed in the latest reported quarter.
Sector classification currently covers about 4% of this portfolio's disclosed value; the remainder includes holdings (e.g. unmapped tickers, options, or other security types) not yet covered by our sector mapping.
Source and citation information
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Recent moves
View source Form 13F filing on SEC.govSold out JAZZ
Sold out 260
Add ANAB
0.0% $94.9M
Sold out CRNX
Add ZYME
0.0% $25.3M
Add CGON
+86.6% $71.5M
Holdings Map
New buyAddUnchangedTrim
Top 10 holdings by weight
Full holdings list this quarter
Showing top 31 holdings (of 33 total)
| # | Ticker | Issuer | Asset Subclass | Weight | Weight Change | Shares Change | 4Q Trend |
|---|---|---|---|---|---|---|---|
| 1 | ZYME | Zymeworks Inc | Stock-Other | 29.19% | +4.78% | — | |
| 2 | ANAB | Anaptysbio Inc | Stock-Other | 25.86% | +7.31% | — | |
| 3 | AKTS | Aktis Oncology Inc | Stock-Other | 7.56% | +3.90% | — | |
| 4 | CGON | Cg Oncology Inc | Stock-Other | 7.10% | +3.93% | +86.55% | |
| 5 | ETON | Eton Pharmaceuticals Inc | Stock-Other | 3.82% | +1.55% | — | |
| 6 | CRSP | CRISPR Therapeutics AG | Stock-Healthcare | 3.68% | +0.88% | — | |
| 7 | ORIC | Oric Pharmaceuticals Inc | Stock-Other | 3.54% | -0.08% | — | |
| 8 | ✓ | Stock-Other | 3.11% | +3.11% | NEW | ||
| 9 | LKFT | Lakefront Biotherapeutic-adr | Stock-Other | 2.43% | +0.31% | — | |
| 10 | NGNE | Neurogene Inc | Stock-Other | 1.94% | +0.85% | — | |
| 11 | STOK | Stoke Therapeutics Inc | Stock-Other | 1.17% | +1.03% | +635.00% | |
| 12 | FULC | Fulcrum Therapeutics Inc | Stock-Other | 1.17% | +1.17% | NEW | |
| 13 | LEGN | Legend Biotech Corp-adr | Stock-Other | 1.12% | +1.12% | NEW | |
| 14 | BBOT | Bridgebio Oncology Therapeut | Stock-Other | 1.05% | -0.02% | — | |
| 15 | MBX | Mbx Biosciences Inc | Stock-Other | 1.04% | +0.06% | -50.00% | |
| 16 | ZBIO | Zenas Biopharma Inc | Stock-Other | 0.97% | +0.31% | — | |
| 17 | ATRA | Atara Biotherapeutics Inc | Stock-Other | 0.87% | +0.85% | +1458.34% | |
| 18 | RLAY | Relay Therapeutics Inc | Stock-Other | 0.63% | -0.17% | -63.36% | |
| 19 | AURA | Aura Biosciences Inc | Stock-Other | 0.58% | +0.58% | NEW | |
| 20 | ✓ | Stock-Other | 0.51% | +0.51% | NEW | ||
| 21 | EIKN | Eikon Therapeutics Inc | Stock-Other | 0.46% | +0.13% | — | |
| 22 | PHVS | Pharvaris N.V. | Stock-Other | 0.40% | +0.40% | NEW | |
| 23 | ✓ | Zura Bio LTD | Stock-Other | 0.34% | +0.04% | — | |
| 24 | PHAT | Phathom Pharmaceuticals Inc | Stock-Other | 0.33% | +0.04% | — | |
| 25 | NRIX | Nurix Therapeutics Inc | Stock-Other | 0.32% | +0.32% | NEW | |
| 26 | ERAS | Erasca Inc | Stock-Other | 0.29% | -0.33% | -63.33% | |
| 27 | ✓ | Stock-Other | 0.27% | +0.27% | NEW | ||
| 28 | AARD | Aardvark Therapeutics Inc | Stock-Other | 0.12% | +0.12% | NEW | |
| 29 | ✓ | Helix Acquisition CORP Iii | Stock-Other | 0.10% | +0.01% | — | |
| 30 | MREO | Mereo Biopharma Group Pl-adr | Stock-Other | 0.02% | -0.17% | -92.52% | |
| 31 | SRZNW | Surrozen Inc-cw25 | Stock-Other | 0.01% | — | — |
Portfolio Performance
Performance for Q3 2026
+24.4%
Performance Last 4 Quarters
+108.3%
Based on 89% of reported portfolio value with available pricing
- Stdev
- +37%
- Beta
- +1.34
- Alpha
- -14.4%
- Max Drawdown
- -51.7%
- Annualized Perf
- +6.2%
- Batting Avg vs S&P
- +36.1%
- Sortino
- +0.57
- Stutzer
- +0.1
- Treynor
- +0.09
- Sterling
- +0.19
- Calmar
- +0.12
- Information Ratio
- -0.23
- Tracking Error
- +33%
- Stdev Down
- +21.9%
- Winning Months %
- +47.2%
- Losing Months %
- +52.8%
- Best 12 Months
- +114.4%
- Worst 12 Months
- -46.3%
- Efficiency Ratio
- +0.07
- Sharpe
- +0.34
- Stdev Sectors
- 0%
- Skewness
- +0.52
- Kurtosis
- +0.62
- Upside Potential
- +2.49
Reported value over time
Sector allocation
Sector allocation over time
Quarterly history
| Period | Holdings | Total value | Stability | Top holdings | |
|---|---|---|---|---|---|
| 2026 Q2 | 33 | $2.1B | 60 | ||
| 2026 Q1 | 30 | $2.4B | 37 | ||
| 2025 Q4 | 30 | $2.2B | 61 | ||
| 2025 Q3 | 30 | $2.1B | 81 | ||
| 2025 Q2 | 37 | $1.7B | 0 | ||
| 2025 Q1 | 46 | $1.7B | 100 | ||
| 2024 Q4 | 59 | $2.6B | 0 | ||
| 2024 Q3 | 64 | $2.9B | 0 | ||
| 2024 Q2 | 55 | $3.3B | 0 | ||
| 2024 Q1 | 59 | $4.0B | 0 | ||
| 2023 Q4 | 51 | $3.9B | 0 | ||
| 2023 Q3 | 51 | $3.0B | 0 | ||
| 2023 Q2 | 53 | $4.1B | 0 | ||
| 2023 Q1 | 58 | $3.1B | 0 | ||
| 2022 Q4 | 66 | $3.3B | 0 | ||
| 2022 Q3 | 76 | $3.4B | 0 | ||
| 2022 Q2 | 80 | $2.9B | 0 | ||
| 2022 Q1 | 87 | $3.2B | 0 | ||
| 2021 Q4 | 76 | $3.1B | 0 | ||
| 2021 Q3 | 71 | $2.9B | 0 | ||
| 2021 Q2 | 72 | $2.7B | 91 | ||
| 2021 Q1 | 71 | $2.3B | 57 | ||
| 2020 Q4 | 67 | $1.9B | 61 | ||
| 2020 Q3 | 50 | $1.4B | 62 | ||
| 2020 Q2 | 49 | $1.4B | 98 | ||
| 2020 Q1 | 51 | $957.2M | 59 | ||
| 2019 Q4 | 44 | $1.1B | 76 | ||
| 2019 Q3 | 41 | $791.9M | 59 | ||
| 2019 Q2 | 40 | $989.6M | 65 | ||
| 2019 Q1 | 41 | $1.1B | 79 | ||
| 2018 Q4 | 54 | $999.4M | 75 | ||
| 2018 Q3 | 51 | $1.1B | 48 | ||
| 2018 Q2 | 35 | $1.1B | 69 | ||
| 2018 Q1 | 32 | $997.0M | 48 | ||
| 2017 Q4 | 31 | $888.1M | 72 | ||
| 2017 Q3 | 40 | $750.3M | 88 | ||
| 2017 Q2 | 36 | $563.2M | 75 | ||
| 2017 Q1 | 33 | $395.6M | 84 | ||
| 2016 Q4 | 30 | $299.4M | 87 | ||
| 2016 Q3 | 31 | $325.9M | 88 | ||
| 2016 Q2 | 32 | $253.6M | 87 | ||
| 2016 Q1 | 37 | $286.2M | 82 | ||
| 2015 Q4 | 31 | $318.4M | 78 | ||
| 2015 Q3 | 25 | $219.7M | 56 | ||
| 2015 Q2 | 27 | $299.9M | 69 | ||
| 2015 Q1 | 24 | $300.1M | 85 | ||
| 2014 Q4 | 22 | $197.6M | 0 |
Holding changes this quarter
EcoR1 Capital, LLC's most significant position changes for 2026-06-30: Sold out: Jazz Pharmaceuticals plc (JAZZ); Sold out: Centessa Pharmaceuticals-adr (260); Sold out: Crinetics Pharmaceuticals In (CRNX); New buy: ; Sold out: Xencor Inc (XNCR).
| # | Ticker | Issuer | Weight Change | Shares Change | Action |
|---|---|---|---|---|---|
| 1 | ANAB | Anaptysbio Inc | +7.3% | — | Unchanged |
| 2 | ZYME | Zymeworks Inc | +4.8% | — | Unchanged |
| 3 | CGON | Cg Oncology Inc | +3.9% | +86.55% | Add |
| 4 | AKTS | Aktis Oncology Inc | +3.9% | — | Unchanged |
| 5 | ✓ | +3.1% | NEW | New buy | |
| 6 | ETON | Eton Pharmaceuticals Inc | +1.6% | — | Unchanged |
| 7 | FULC | Fulcrum Therapeutics Inc | +1.2% | NEW | New buy |
| 8 | LEGN | Legend Biotech Corp-adr | +1.1% | NEW | New buy |
| 9 | STOK | Stoke Therapeutics Inc | +1% | +635.00% | Add |
| 10 | CRSP | CRISPR Therapeutics AG | +0.9% | — | Unchanged |
| 11 | ATRA | Atara Biotherapeutics Inc | +0.9% | +1458.34% | Add |
| 12 | NGNE | Neurogene Inc | +0.9% | — | Unchanged |
| 13 | AURA | Aura Biosciences Inc | +0.6% | NEW | New buy |
| 14 | ✓ | +0.5% | NEW | New buy | |
| 15 | PHVS | Pharvaris N.V. | +0.4% | NEW | New buy |
| 16 | NRIX | Nurix Therapeutics Inc | +0.3% | NEW | New buy |
| 17 | ZBIO | Zenas Biopharma Inc | +0.3% | — | Unchanged |
| 18 | LKFT | Lakefront Biotherapeutic-adr | +0.3% | — | Unchanged |
| 19 | ✓ | +0.3% | NEW | New buy | |
| 20 | EIKN | Eikon Therapeutics Inc | +0.1% | — | Unchanged |
| 21 | AARD | Aardvark Therapeutics Inc | +0.1% | NEW | New buy |
| 22 | MBX | Mbx Biosciences Inc | +0.1% | -50.00% | Trim |
| 23 | PHAT | Phathom Pharmaceuticals Inc | 0% | — | Unchanged |
| 24 | ✓ | Zura Bio LTD | 0% | — | Unchanged |
| 25 | ✓ | Helix Acquisition CORP Iii | 0% | — | Unchanged |
| 26 | SRZNW | Surrozen Inc-cw25 | — | — | Unchanged |
| 27 | BBOT | Bridgebio Oncology Therapeut | 0% | — | Unchanged |
| 28 | ORIC | Oric Pharmaceuticals Inc | -0.1% | — | Unchanged |
| 29 | IBIO | Ibio Inc | -0.1% | EXIT | Sold out |
| 30 | PRLD | Prelude Therapeutics Inc | -0.1% | EXIT | Sold out |
| 31 | RLAY | Relay Therapeutics Inc | -0.2% | -63.36% | Trim |
| 32 | MREO | Mereo Biopharma Group Pl-adr | -0.2% | -92.52% | Trim |
| 33 | REPL | Replimune Group Inc | -0.3% | EXIT | Sold out |
| 34 | ERAS | Erasca Inc | -0.3% | -63.33% | Trim |
| 35 | XNCR | Xencor Inc | -1.1% | EXIT | Sold out |
| 36 | CRNX | Crinetics Pharmaceuticals In | -6.6% | EXIT | Sold out |
| 37 | 260 | Centessa Pharmaceuticals-adr | -10.8% | EXIT | Sold out |
| 38 | JAZZ | Jazz Pharmaceuticals plc | -13.7% | EXIT | Sold out |
Filing History
FAQ
What is EcoR1 Capital, LLC and what type of investor is it?
EcoR1 Capital, LLC is an investment manager that files SEC Form 13F quarterly, disclosing its U.S. public equity holdings to regulators. As of the most recent reporting period (2026-06-30), the firm manages a tracked equity portfolio valued at approximately $2.1B, spread across 33 disclosed positions.
What are EcoR1 Capital, LLC's largest equity positions?
Based on the latest 13F filing, EcoR1 Capital, LLC's top holdings by market value are:
1. Zymeworks Inc (ZYME) — $600.4M (29.2%)
2. Anaptysbio Inc (ANAB) — $531.9M (25.9%)
3. Aktis Oncology Inc (AKTS) — $155.5M (7.6%)
4. Cg Oncology Inc (CGON) — $146.1M (7.1%)
5. Eton Pharmaceuticals Inc (ETON) — $78.6M (3.8%)
What changes did EcoR1 Capital, LLC make in its most recent portfolio filing?
In the latest reported quarter, EcoR1 Capital, LLC made 23 notable position adjustments: 9 new positions were initiated, 3 existing holdings were added to, 4 positions were partially reduced, and 7 were completely exited. The largest of these moves: Sold out: Jazz Pharmaceuticals plc (JAZZ); Sold out: Centessa Pharmaceuticals-adr (260); Sold out: Crinetics Pharmaceuticals In (CRNX); New buy: ; Sold out: Xencor Inc (XNCR)
What sectors does EcoR1 Capital, LLC focus on?
EcoR1 Capital, LLC is concentrated in the following sectors based on its current disclosed equity portfolio:
• Health Care: 100.0%
Investment Profile
EcoR1 Capital, LLC returned an annualized 6.2% over the trailing 36 months — underperforming the S&P 500 by 14.4 points — based on a reconstructed track record of its disclosed 13F positions, with a beta of 1.34 (more volatile than the market) and a 36% quarterly batting average against the index.
Its portfolio is concentrated and fast-trading, with 100.0% of the portfolio concentrated in Health Care.
Its turnover score has risen from 0 to 60 over the past 4 quarters — a shift toward more active trading.
It has added to its ANAB position over the past two quarters (+$149.9M, now $531.9M), while trimming MBX over the same stretch (-$45.5M, still holding $21.4M).
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Developer Access
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