Skip to content
Shameless Cloning

Search Shameless Cloning

Search superinvestors, stocks, insiders and members of Congress

Q2 2026 13F · SEC CIK 1587114

EcoR1 Capital, LLC

Hedge fundFiled 2026-08-14 for Q2 2026. Open the filing ↗ · All SEC filings ↗

Reported 13F value
$2.0B
Reported positions
31
Top holdings a year, 3 yrs
+3.0%
Assets under management
$3.4B

EcoR1 Capital, LLC is a hedge fund that reported 31 positions worth $2.0B in its Q2 2026 13F, filed 2026-08-14. Its largest holdings were Zymeworks Inc (ZYME, 29.8%), Anaptysbio Inc (ANAB, 26.4%), Aktis Oncology Inc (AKTS, 7.7%). A portfolio copying its top holdings returned 3.0% a year over the last 3 years, against 20.4% for the S&P 500.

EcoR1 Capital, LLC holdings all 31 positions.

Weights are shares of the filer's total reported 13F value, compared with Q1 2026. Share changes may reflect splits; weight changes also reflect price moves. A 13F shows long US-listed positions only, up to 135 days after the fact.

EcoR1 Capital, LLC 13F holdings
Stock% of 13F valueShare changeReported value
ZYMEZymeworks Inc29.8%+0.0%$600.4M
ANABAnaptysbio Inc26.4%+0.0%$531.9M
AKTSAktis Oncology Inc7.7%+0.0%$155.5M
CGONCg Oncology Inc5.3%+35.6%$106.2M
ETONEton Pharmaceuticals Inc3.9%+0.0%$78.6M
CRSPCrispr Therapeutics AG3.8%+0.0%$75.8M
ORICOric Pharmaceuticals Inc3.6%+0.0%$72.9M
TRAXFirst Tracks Biotherapeutics3.2%—$63.9M
GLPGFLakefront Biotherapeutics2.5%+0.0%$50.0M
NGNENeurogene Inc2.0%+0.0%$40.0M
STOKStoke Therapeutics Inc1.2%+635.0%$24.0M
FULCFulcrum Therapeutics Inc1.2%—$24.0M
LEGNLegend Biotech Corp1.1%—$23.1M
BBOTBridgebio Oncology Therapeut1.1%+0.0%$21.5M
MBXMbx Biosciences Inc1.1%-50.0%$21.4M
ZBIOZenas Biopharma Inc1.0%+0.0%$20.0M
ATRAAtara Biotherapeutics Inc0.9%+1458.3%$17.8M
RLAYRelay Therapeutics Inc0.6%-63.4%$13.1M
AURAAura Biosciences Inc0.6%—$11.8M
ODTXOdyssey Therapeutics, Inc.0.5%—$10.4M
EIKNEikon Therapeutics Inc0.5%+0.0%$9.6M
PHVSPharvaris N V0.4%—$8.1M
ZURAZura Bio Ltd0.3%+0.0%$7.0M
PHATPhathom Pharmaceuticals Inc Com0.3%+0.0%$6.8M
NRIXNurix Therapeutics Inc0.3%—$6.6M
ERASErasca, Inc.0.3%-63.3%$6.0M
ELOXEloxx Pharmaceuticals Inc0.3%—$5.6M
AARDAardvark Therapeutics Inc0.1%—$2.3M
HLXCHelix Acquisition Corp III0.1%+0.0%$2.1M
MREOMereo Biopharma Group PLC0.0%-92.5%$318K
SRZNWSurrozen Inc0.0%+0.0%$115K

What EcoR1 Capital, LLC bought and sold in Q2 2026, against Q1 2026.

New positions

Added to

Reduced

Sold out

Share counts compared with the Q1 2026 13F; a split also changes share counts.

How the holdings did against the S&P 500.

1 year
+109.9% /yr
S&P 500 +20.1%
3 years
+3.0% /yr
S&P 500 +20.4%
5 years
-6.1% /yr
S&P 500 +11.6%

A portfolio of the filer's 20 largest 13F positions, weighted by value, bought the trading day after each 13F was filed and held until the next one was: what copying this filer could have earned. 13Fs show long US-listed positions only, so this is an estimate of the stock picks, not the fund's reported returns.

Reported 13F value by quarter.

13F value by quarter
Quarter13F valuePositions
Q2 2026$2.0B31
Q1 2026$2.3B29
Q4 2025$2.2B28
Q3 2025$2.1B30
Q2 2025$1.7B36
Q1 2025$1.7B44
Q4 2024$2.5B55
Q3 2024$2.9B63
Q2 2024$3.3B55
Q1 2024$3.9B57
Q4 2023$3.9B51
Q3 2023$2.9B49

Questions about EcoR1 Capital, LLC's portfolio

What stocks does EcoR1 Capital, LLC own?

EcoR1 Capital, LLC's latest 13F, for Q2 2026 and filed Aug 14, 2026, lists 31 positions worth $2.0B. The largest are Zymeworks Inc (ZYME) at 29.8%, Anaptysbio Inc (ANAB) at 26.4%, Aktis Oncology Inc (AKTS) at 7.7%, Cg Oncology Inc (CGON) at 5.3% and Eton Pharmaceuticals Inc (ETON) at 3.9%.

What did EcoR1 Capital, LLC buy last quarter?

In Q2 2026, EcoR1 Capital, LLC added a new position in First Tracks Biotherapeutics (TRAX), a new position in Fulcrum Therapeutics Inc (FULC), a new position in Legend Biotech Corp (LEGN), a new position in Aura Biosciences Inc (AURA), a new position in Odyssey Therapeutics, Inc. (ODTX), Atara Biotherapeutics Inc (ATRA) (+1458.3% shares), Stoke Therapeutics Inc (STOK) (+635.0% shares) and Cg Oncology Inc (CGON) (+35.6% shares), compared with its Q1 2026 filing.

What did EcoR1 Capital, LLC sell last quarter?

In Q2 2026, EcoR1 Capital, LLC sold all of Jazz Pharmaceuticals PLC (JAZZ), sold all of Centessa Pharmaceuticals PLC (CNTA), sold all of Crinetics Pharmaceuticals in (CRNX), sold all of Xencor Inc (XNCR), sold all of Replimune Group Inc (REPL), Mereo Biopharma Group PLC (MREO) (-92.5% shares), Relay Therapeutics Inc (RLAY) (-63.4% shares) and Erasca, Inc. (ERAS) (-63.3% shares), compared with its Q1 2026 filing.

How has EcoR1 Capital, LLC's portfolio performed?

A portfolio copying EcoR1 Capital, LLC's 20 largest 13F holdings each quarter, from the day each filing was public, returned +3.0% a year over the last 3 years, against +20.4% for the S&P 500. Over 1 year: +109.9% against +20.1%. Over 5 years: -6.1% a year against +11.6%.

When is EcoR1 Capital, LLC's next 13F filing due?

13F filings are due 45 days after each quarter ends. EcoR1 Capital, LLC's filing for the quarter ending Sep 30, 2026 is due by Nov 14, 2026; this page updates the day after it is published.

How much money does EcoR1 Capital, LLC manage?

EcoR1 Capital, LLC reported $3.4B of regulatory assets under management on its latest SEC Form ADV. Its 13F, which covers only US-listed stocks and options, totals $2.0B.