EcoR1 Capital, LLC
CIK
1587114
Location
San Francisco, CA
Portfolio Value
Mid
$2,210,512,444
Diversification
Diversified
Filing Date
Global Rank
#1,092
/ 8,605
▲ 62
· as of Mar 2026
Top Industry
Biotechnology
97.5%
3Y Alpha vs SPY
-16.5%
Period ended 3 months ago
Filed May 15, 2026 · 55d
25 quarters · since Mar 2020
Clone Performance
Jul 2023–Jul 2026 · vs SPYHypothetical growth of cloning every reported 13F position and rebalancing on each filing, indexed to the same start.
Cloned portfolio
+5.8%
SPY
+76.5%
Annualised alpha
-19.0%
Max drawdown
−62.9%
Estimate. 13F holdings are quarter-lagged and long-only, so the clone rebalances about 45 days after each period end — when the filing becomes public — and excludes options and short positions. Past performance does not predict future results.
Portfolio Concentration
28 positions · as of Mar 31, 2026 · Δ vs Dec 31, 2025Top Position
26.0%
−3.2 pts
Top 5
72.4%
+3.3 pts
Top 10
88.9%
+4.9 pts
HHI
1,315
Diversified−66
Portfolio Trend
25 quarters · across all stocks
Sector Breakdown
As of Mar 31, 2026| Sector | % Portfolio | Value |
|---|---|---|
| Healthcare | 99.9% | $2,208,480,444 |
| Financial Services | 0.1% | $2,032,000 |
Last Quarter's Activity
Export CSVAdded To
Positions the filer increased
4 positions
| Ticker | Company | Δ Shares | Shares | Value | Open |
|---|---|---|---|---|---|
| MREO | Mereo BioPharma Group plc | +5,512,389 | 13,368,855 | $4,411,722 | |
| CNTA | Centessa Pharmaceuticals plc | +3,295,800 | 6,410,800 | $254,636,976 | |
| ETON | Eton Pharmaceuticals, Inc. | +141,394 | 2,171,938 | $53,603,429 | |
| CGON | CG Oncology, Inc. | +37,200 | 1,102,000 | $74,583,360 | |
| No positions match the current search. | |||||
Trimmed
Positions the filer reduced
4 positions
New Positions
Positions the filer opened this quarter
10 positions
| Ticker | Company | Shares | Value | Open |
|---|---|---|---|---|
| AKTS | Aktis Oncology, Inc. | 4,824,469 | $86,309,750 | |
| RLAY | Relay Therapeutics, Inc. | 1,904,762 | $18,952,381 | |
| ERAS | Erasca, Inc. | 900,000 | $14,562,000 | |
| EIKN | Eikon Therapeutics, Inc. | 732,606 | $7,750,971 | |
| REPL | Replimune Group, Inc. | 1,000,000 | $7,650,000 | |
| ZURA | Zura Bio Ltd | 1,179,715 | $7,019,304 | |
| PHAT | Phathom Pharmaceuticals, Inc. | 625,000 | $6,943,750 | |
| STOK | Stoke Therapeutics, Inc. | 100,000 | $3,256,000 | |
| PRLD | Prelude Therapeutics Inc | 947,049 | $3,238,907 | |
| HLXC | Helix Acquisition Corp. III | 200,000 | $2,032,000 | |
| No positions match the current search. | ||||
Sold Out
Positions the filer fully exited
8 positions
| Ticker | Company | Shares | Value | Open |
|---|---|---|---|---|
| IMNM | Immunome Inc. | 2,855,590 | $61,338,073 | |
| GPCR | Structure Therapeutics Inc. | 334,380 | $23,256,129 | |
| PCVX | Vaxcyte, Inc. | 450,000 | $20,763,000 | |
| AQST | Aquestive Therapeutics, Inc. | 2,625,000 | $16,957,500 | |
| VYGR | Voyager Therapeutics, Inc. | 4,002,847 | $15,731,188 | |
| MNKD | Mannkind Corp | 1,660,000 | $9,412,200 | |
| EOLS | Evolus, Inc. | 675,000 | $4,488,750 | |
| CAMP | Camp4 Therapeutics Corp | 325,000 | $1,992,250 | |
| No positions match the current search. | ||||
28 positions ·
$2,210,512,444 total
· as of Mar 31, 2026
| Ticker | Company | Type | Shares | Value (USD) | % of Portfolio | History |
|---|---|---|---|---|---|---|
| ZYME |
Zymeworks Inc.
Healthcare
|
Held | 22,970,388 | $575,178,515 | 26.02% | |
| JAZZ |
Jazz Pharmaceuticals plc
Healthcare
|
Held | 1,706,469 | $322,607,964 | 14.59% | |
| ANAB |
Anaptysbio, Inc
Healthcare
|
Held | 7,880,094 | $291,353,079 | 13.18% | |
| CNTA |
Centessa Pharmaceuticals plc
Healthcare
|
Added | 6,410,800 | $254,636,976 | 11.52% | |
| CRNX |
Crinetics Pharmaceuticals, Inc.
Healthcare
|
Held | 4,288,120 | $155,744,518 | 7.05% | |
| AKTS |
Aktis Oncology, Inc.
Healthcare
|
NEW | 4,824,469 | $86,309,750 | 3.90% | |
| ORIC |
Oric Pharmaceuticals, Inc.
Healthcare
|
Held | 6,728,116 | $85,245,229 | 3.86% | |
| CGON |
CG Oncology, Inc.
Healthcare
|
Added | 1,102,000 | $74,583,360 | 3.37% | |
| CRSP |
CRISPR Therapeutics AG
Healthcare
|
Held | 1,389,276 | $66,087,859 | 2.99% | |
| ETON |
Eton Pharmaceuticals, Inc.
Healthcare
|
Added | 2,171,938 | $53,603,429 | 2.42% | |
| LKFT |
Lakefront Biotherapeutics NV
Healthcare
|
Held | 1,667,119 | $50,013,570 | 2.26% | |
| XNCR |
Xencor Inc
Healthcare
|
Reduced | 2,183,000 | $26,326,980 | 1.19% | |
| NGNE |
Neurogene Inc.
Healthcare
|
Held | 1,271,342 | $25,630,254 | 1.16% | |
| BBOT |
BridgeBio Oncology Therapeutics, Inc.
Healthcare
|
Held | 2,823,126 | $25,266,977 | 1.14% | |
| MBX |
MBX Biosciences, Inc.
Healthcare
|
Reduced | 777,000 | $23,193,450 | 1.05% | |
| RLAY |
Relay Therapeutics, Inc.
Healthcare
|
NEW | 1,904,762 | $18,952,381 | 0.86% | |
| ZBIO |
Zenas BioPharma, Inc.
Healthcare
|
Held | 789,500 | $15,434,725 | 0.70% | |
| ERAS |
Erasca, Inc.
Healthcare
|
NEW | 900,000 | $14,562,000 | 0.66% | |
| EIKN |
Eikon Therapeutics, Inc.
Healthcare
|
NEW | 732,606 | $7,750,971 | 0.35% | |
| REPL |
Replimune Group, Inc.
Healthcare
|
NEW | 1,000,000 | $7,650,000 | 0.35% | |
| ZURA |
Zura Bio Ltd
Healthcare
|
NEW | 1,179,715 | $7,019,304 | 0.32% | |
| PHAT |
Phathom Pharmaceuticals, Inc.
Healthcare
|
NEW | 625,000 | $6,943,750 | 0.31% | |
| MREO |
Mereo BioPharma Group plc
Healthcare
|
Added | 13,368,855 | $4,411,722 | 0.20% | |
| STOK |
Stoke Therapeutics, Inc.
Healthcare
|
NEW | 100,000 | $3,256,000 | 0.15% | |
| PRLD |
Prelude Therapeutics Inc
Healthcare
|
NEW | 947,049 | $3,238,907 | 0.15% | |
| IBIO |
iBio, Inc.
Healthcare
|
Reduced | 1,583,000 | $3,007,700 | 0.14% | |
| HLXC |
Helix Acquisition Corp. III
Financial Services
|
NEW | 200,000 | $2,032,000 | 0.09% | |
| ATRA |
Atara Biotherapeutics, Inc.
Healthcare
|
Reduced | 99,593 | $471,074 | 0.02% |