Latest EcoR1 Capital, LLC Stock Portfolio
$2.36Billion– No. of Holdings #29
EcoR1 Capital, LLC Performance:
2026 Q1: 4.35%YTD: 4.35%2025: 35.99%
Performance for 2026 Q1 is 4.35%, and YTD is 4.35%, and 2025 is 35.99%.
About EcoR1 Capital, LLC and 13F Hedge Fund Stock Holdings
EcoR1 Capital, LLC is a hedge fund based in San Francisco, CA. On 2026-05-15, the fund reported it's updated stock portfolio. In the 13F Holdings report, EcoR1 Capital, LLC reported an equity portfolio of $2.4 Billions as of 31 Mar, 2026.
The top stock holdings of EcoR1 Capital, LLC are ZYME, ANAB, JAZZ. The fund has invested 24.4% of it's portfolio in ZYMEWORKS INC and 18.6% of portfolio in ANAPTYSBIO INC.
The fund managers got completely rid off IMMUNOME INC (IMNM), STRUCTURE THERAPEUTICS INC and VAXCYTE INC (PCVX) stocks. They significantly reduced their stock positions in ATARA BIOTHERAPEUTICS INC (ATRA), MBX BIOSCIENCES INC and XENCOR INC (XNCR). EcoR1 Capital, LLC opened new stock positions in AKTIS ONCOLOGY INC, RELAY THERAPEUTICS INC (RLAY) and ERASCA INC (ERAS). The fund showed a lot of confidence in some stocks as they added substantially to CENTESSA PHARMACEUTICALS PLC (CNTA), MEREO BIOPHARMA GROUP PLC (MREO) and CG ONCOLOGY INC.
The top stock holdings of EcoR1 Capital, LLC are ZYME, ANAB, JAZZ. The fund has invested 24.4% of it's portfolio in ZYMEWORKS INC and 18.6% of portfolio in ANAPTYSBIO INC.
The fund managers got completely rid off IMMUNOME INC (IMNM), STRUCTURE THERAPEUTICS INC and VAXCYTE INC (PCVX) stocks. They significantly reduced their stock positions in ATARA BIOTHERAPEUTICS INC (ATRA), MBX BIOSCIENCES INC and XENCOR INC (XNCR). EcoR1 Capital, LLC opened new stock positions in AKTIS ONCOLOGY INC, RELAY THERAPEUTICS INC (RLAY) and ERASCA INC (ERAS). The fund showed a lot of confidence in some stocks as they added substantially to CENTESSA PHARMACEUTICALS PLC (CNTA), MEREO BIOPHARMA GROUP PLC (MREO) and CG ONCOLOGY INC.
EcoR1 Capital, LLC Equity Portfolio Value
Last Reported on: 15 May, 2026
EcoR1 Capital, LLC Annual Return Estimates Vs S&P 500
Our best estimate is that EcoR1 Capital, LLC made a return of 4.35% in the last quarter. In trailing 12 months, it's portfolio return was 90.05%.
- Performance
- S&P 500
New Buys
| Ticker | $ Bought |
|---|---|
| aktis oncology inc | 86,309,800 |
| relay therapeutics inc | 18,952,400 |
| erasca inc | 14,562,000 |
| eikon therapeutics inc | 7,750,970 |
| replimune group inc | 7,650,000 |
| zura bio ltd | 7,019,300 |
| phathom pharmaceuticals inc | 6,943,750 |
| stoke therapeutics inc | 3,256,000 |
New stocks bought by EcoR1 Capital, LLC
Additions
| Ticker | % Inc. |
|---|---|
| centessa pharmaceuticals plc | 92.62 |
| mereo biopharma group plc | 70.16 |
| cg oncology inc | 42.75 |
| eton pharmaceuticals inc | 6.96 |
Additions to existing portfolio by EcoR1 Capital, LLC
Reductions
| Ticker | % Reduced |
|---|---|
| atara biotherapeutics inc | -82.62 |
| mbx biosciences inc | -63.41 |
| xencor inc | -32.85 |
| ibio inc | -28.95 |
EcoR1 Capital, LLC reduced stake in above stock
Sold off
| Ticker | $ Sold |
|---|---|
| voyager therapeutics inc | -15,731,200 |
| immunome inc | -61,338,100 |
| aquestive therapeutics inc | -16,957,500 |
| mannkind corp | -9,412,200 |
| nuvation bio inc | -8,631,460 |
| evolus inc | -4,488,750 |
| vaxcyte inc | -20,763,000 |
| structure therapeutics inc | -23,256,100 |
EcoR1 Capital, LLC got rid off the above stocks
Sector Distribution
EcoR1 Capital, LLC has about 61.7% of it's holdings in Healthcare sector.
- Healthcare
- Others
| Sector | % |
|---|---|
| Healthcare | 61.7 |
| Others | 38.3 |
Market Cap. Distribution
EcoR1 Capital, LLC has about 13.8% of it's portfolio invested in the large-cap and mega-cap stocks.
- UNALLOCATED
- SMALL-CAP
- MID-CAP
- LARGE-CAP
| Category | % |
|---|---|
| UNALLOCATED | 38.3 |
| SMALL-CAP | 27.3 |
| MID-CAP | 20.3 |
| LARGE-CAP | 13.8 |
Stocks belong to which Index?
About 57% of the stocks held by EcoR1 Capital, LLC either belong to S&P 500 or RUSSELL 2000 index.
- RUSSELL 2000
- Others
| Index | % |
|---|---|
| RUSSELL 2000 | 57 |
| Others | 43 |
EcoR1 Capital, LLC Holdings Map
This heatmap illustrates the top 50 positions within the fund's portfolio.
Current Stock Holdings of EcoR1 Capital, LLC
EcoR1 Capital, LLC has 29 stocks in it's portfolio. About 88.9% of the portfolio is in top 10 stocks. CRNX proved to be the most loss making stock for the portfolio. CNTA was the most profitable stock for EcoR1 Capital, LLC last quarter.
Last Reported on: 15 May, 2026| Ticker | Namesorted ascending | % Portfolio | Shares Held | $ Value | Type | % Change | Options | |
|---|---|---|---|---|---|---|---|---|
| ANAB | anaptysbio inc | 18.55 | 11,820,100 | 437,030,000 | unchanged | 0.00 | ||
| AQST | aquestive therapeutics inc | 0.00 | 0.00 | 0.00 | sold off | -100 | ||
| ATRA | atara biotherapeutics inc | 0.02 | 99,593 | 471,075 | reduced | -82.62 | ||
| CNTA | centessa pharmaceuticals plc | 10.11 | 6,000,000 | 238,320,000 | added | 92.62 | ||
| CRNX | crinetics pharmaceuticals in | 6.61 | 4,288,120 | 155,745,000 | unchanged | 0.00 | ||
| CRSP | crispr therapeutics ag | 2.81 | 1,389,280 | 66,087,900 | unchanged | 0.00 | ||
| EOLS | evolus inc | 0.00 | 0.00 | 0.00 | sold off | -100 | ||
| ERAS | erasca inc | 0.62 | 900,000 | 14,562,000 | new | |||
| ETON | eton pharmaceuticals inc | 2.28 | 2,171,940 | 53,603,400 | added | 6.96 | ||
| GLPG | galapagos nv | 2.12 | 1,667,120 | 50,013,600 | unchanged | 0.00 | ||
| IBIO | ibio inc | 0.13 | 1,583,000 | 3,007,700 | reduced | -28.95 | ||
| IMNM | immunome inc | 0.00 | 0.00 | 0.00 | sold off | -100 | ||
| JAZZ | jazz pharmaceuticals plc | 13.69 | 1,706,470 | 322,608,000 | unchanged | 0.00 | ||
| MNKD | mannkind corp | 0.00 | 0.00 | 0.00 | sold off | -100 | ||
| MREO | mereo biopharma group plc | 0.19 | 13,368,900 | 4,411,720 | added | 70.16 | ||
| NUVB | nuvation bio inc | 0.00 | 0.00 | 0.00 | sold off | -100 | ||
| ORIC | oric pharmaceuticals inc | 3.62 | 6,728,120 | 85,245,200 | unchanged | 0.00 | ||
| PCVX | vaxcyte inc | 0.00 | 0.00 | 0.00 | sold off | -100 | ||
| PHAT | phathom pharmaceuticals inc | 0.30 | 625,000 | 6,943,750 | new | |||
| PRLD | prelude therapeutics inc | 0.14 | 947,049 | 3,238,910 | new | |||