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Livermore
Livermore
ZHEN

EcoR1 Capital, LLC

SEC CIK
0001587114
Latest filing
Aug 14, 2026

The latest 13F from EcoR1 Capital, LLC covers Q2 2026 (filed Aug 14, 2026): 31 long positions worth $2.02B. The top 10 holdings make up 88.0% of the portfolio, and the largest is Zymeworks Inc. (ZYME) at 29.8%. Livermore has 23 filings on Form 13F from this institution, going back to Q1 2021.

What changed in Q2 2026

Share counts compared with Q1 2026: how many positions were new, added to, reduced or sold out, and the biggest buys and sells. Dollar amounts are estimated at the quarter-end prices implied by the filing.

Full comparison
New
9
Est. +$155.7M
Added
3
Est. +$65.3M
Reduced
4
Est. −$58.4M
Sold out
7
Est. −$756.9M

Top 5 holdings

Share of this quarter's portfolio value

  1. ZYMEZymeworks Inc.
    29.8%$600.4MHistory
  2. ANABAnaptysbio, Inc
    26.4%$531.9MHistory
  3. AKTSAktis Oncology, Inc.
    7.7%$155.5MHistory
  4. CGONCG Oncology, Inc.
    5.3%$106.2MHistory
  5. ETONEton Pharmaceuticals, Inc.
    3.9%$78.6MHistory

Biggest buys

New and added positions, by estimated amount bought

  1. TRAXFirst Tracks Biotherapeutics, Inc.
    +$63.9MNewHistory
  2. CGONCG Oncology, Inc.
    +$27.9MAddedHistory
  3. FULCFulcrum Therapeutics, Inc.
    +$24.0MNewHistory
  4. LEGNLegend Biotech Corp
    +$23.1MNewHistory
  5. STOKStoke Therapeutics, Inc.
    +$20.8MAddedHistory

Largest weight increases

New and added positions, by percentage points of the portfolio gained

  1. TRAXFirst Tracks Biotherapeutics, Inc.
    +3.17 pp0.0% → 3.2%History
  2. CGONCG Oncology, Inc.
    +2.08 pp3.2% → 5.3%History
  3. FULCFulcrum Therapeutics, Inc.
    +1.19 pp0.0% → 1.2%History
  4. LEGNLegend Biotech Corp
    +1.15 pp0.0% → 1.1%History
  5. STOKStoke Therapeutics, Inc.
    +1.05 pp0.1% → 1.2%History

Biggest sells

Reduced and sold-out positions, by estimated amount sold

  1. JAZZJazz Pharmaceuticals plc
    −$322.6MSold outHistory
  2. CNTACentessa Pharmaceuticals plc
    −$238.3MSold outHistory
  3. CRNXCrinetics Pharmaceuticals, Inc.
    −$155.7MSold outHistory
  4. XNCRXencor Inc
    −$26.3MSold outHistory
  5. RLAYRelay Therapeutics, Inc.
    −$22.6MReducedHistory

Largest weight decreases

Reduced and sold-out positions, by percentage points of the portfolio lost

  1. JAZZJazz Pharmaceuticals plc
    −13.79 pp13.8% → 0.0%History
  2. CNTACentessa Pharmaceuticals plc
    −10.19 pp10.2% → 0.0%History
  3. CRNXCrinetics Pharmaceuticals, Inc.
    −6.66 pp6.7% → 0.0%History
  4. XNCRXencor Inc
    −1.13 pp1.1% → 0.0%History
  5. REPLReplimune Group, Inc.
    −0.33 pp0.3% → 0.0%History

Metrics

13F metrics for Q2 2026, computed only from the numbers in the filings. Definitions below.

Portfolio value
$2.02B
−$323.2M (−13.8%) vs. prior quarter
Positions
31
+2 vs. prior quarter
Top 10 concentration
88.0%
Top 10 as share of value
Turnover
10.1%
Q2 2026, one quarter
Average holding period
13.2 quarters
Weighted by value

How these are calculated

  • Portfolio value: the market value of all long positions in the 13F, as reported at quarter end, excluding options.
  • Top 10 concentration: the combined value of the 10 largest positions as a share of portfolio value.
  • Turnover: the smaller of this quarter's estimated purchases and estimated sales, divided by the average of this and last quarter's portfolio value. Estimates multiply the change in shares by the quarter-end price implied by the filing (market value divided by shares); new positions use this quarter's value and sold-out positions last quarter's. Only positions reported in shares count, and it is not calculated when the previous quarter was not filed.
  • Average holding period: how many consecutive quarters each current position has been held (including this one; a quarter without the position or without a filing starts the count over), weighted by this quarter's value. Counting starts with the first 13F in Livermore (Q1 2021), so positions held before then are understated.

13F filings by quarter

22 quarters, going back to Q1 2021. Bars show each quarter's 13F portfolio value; quarters without a filing are left blank.

Peak $3.93B (Q1 2024)

Q1 2021: $2.23BQ2 2021: $2.66BQ3 2021: $2.83BQ4 2021: $3.12BQ1 2022: $3.19BQ2 2022: $2.87BQ3 2022: $3.38BQ4 2022: $3.28BQ1 2023: $3.10BQ2 2023: $3.79BQ3 2023: $2.93BQ4 2023: $3.85BQ1 2024: $3.93BQ2 2024: $3.27BQ3 2024: $2.92BQ4 2024: $2.50BQ1 2025: $1.68BQ2 2025: $1.68BQ3 2025: $2.08BQ4 2025: $2.18BQ1 2026: $2.34BQ2 2026: $2.02B
Q1 2021Q2 2026
13F filings of EcoR1 Capital, LLC by quarter
QuarterFiledPositionsValueTop 3 holdingsChangesFiling
Q2 2026Aug 14, 202631$2.02BZYMEANABAKTSvs. Q1 2026SEC
Q1 2026May 15, 202629$2.34BZYMEANABJAZZvs. Q4 2025SEC
Q4 2025Feb 17, 202628$2.18BZYMEANABJAZZvs. Q3 2025SEC
Q3 2025Nov 14, 202530$2.08BZYMEANABQUREvs. Q2 2025SEC
Q2 2025Aug 14, 202536$1.68BZYMEAPLSJAZZvs. Q1 2025SEC
Q1 2025May 15, 202544$1.68BAPLSJAZZZYMEvs. Q4 2024SEC
Q4 2024Feb 14, 202555$2.50BAPLSZYMECRNXvs. Q3 2024SEC
Q3 2024Nov 14, 202463$2.92BAPLSANABCRNXvs. Q2 2024SEC
Q2 2024Aug 14, 202455$3.27BAPLSPRTASRPTvs. Q1 2024SEC
Q1 2024May 15, 202457$3.93BAPLSPRTAARVNvs. Q4 2023SEC
Q4 2023Feb 14, 202451$3.85BAPLSMRTXPRTAvs. Q3 2023SEC
Q3 2023Nov 14, 202349$2.93BPRTAAPLSMRTXvs. Q2 2023SEC
Q2 2023Aug 14, 202351$3.79BPRTAAPLSSRPTvs. Q1 2023SEC
Q1 2023May 15, 202358$3.10BPRTASRPTAPLSvs. Q4 2022SEC
Q4 2022Feb 14, 202366$3.28BPRTASRPTAPLSvs. Q3 2022SEC
Q3 2022Nov 14, 202275$3.38BPRTAAPLSSRPTvs. Q2 2022SEC
Q2 2022Aug 15, 202278$2.87BPRTAAPLSSRPTvs. Q1 2022SEC
Q1 2022May 16, 202286$3.19BPRTAAPLSLKFTvs. Q4 2021SEC
Q4 2021Feb 14, 202275$3.12BPRTAANABRCUSvs. Q3 2021SEC
Q3 2021Nov 22, 2021Amended69$2.83BPRTAMORFANABvs. Q2 2021SEC
Q2 2021Aug 16, 202172$2.66BPRTAMORFANABvs. Q1 2021SEC
Q1 2021May 17, 202170$2.23BPRTAXNCRMORF–SEC

13D and 13G filings

Companies where EcoR1 Capital, LLC reports owning 5% or more on Schedule 13D or 13G, and its latest filings.

Current stakes of 5% or more

12 companies, largest stake first.

Companies where EcoR1 Capital, LLC owns 5% or more
CompanyLatest formStakeChangeFirst filedLatest filingFiling
ZYMEZymeworks Inc.13D/A30.70%23.0M shares0.00 ppfrom 30.70%Oct 28, 202212 filingsNov 19, 2025SEC
ITOSiTeos Therapeutics, Inc.13D27.90%10.7M shares+13.00 ppfrom 14.90%Feb 16, 20245 filingsMay 16, 2025SEC
ATRAAtara Biotherapeutics, Inc.13G/A17.40%1.55M shares+7.50 ppfrom 9.90%Nov 21, 20234 filingsMay 7, 2026SEC
LKFTLakefront Biotherapeutics NV13D/A13.22%8.71M shares+1.38 ppfrom 11.84%Feb 3, 20228 filingsJul 28, 2025SEC
NGNENeurogene Inc.13G/A9.90%1.44M shares–Feb 16, 20214 filingsNov 14, 2025SEC
ELOXEloxx Pharmaceuticals, Inc.13G9.90%403.6K sharesNewJun 16, 20261 filingJun 16, 2026SEC
AKTSAktis Oncology, Inc.13D9.10%4.86M sharesNewJan 20, 20261 filingJan 20, 2026SEC
TRAXFirst Tracks Biotherapeutics, Inc.13G9.10%3.17M sharesNewApr 22, 20261 filingApr 22, 2026SEC
FULCFulcrum Therapeutics, Inc.13G9.00%6.00M shares0.00 ppfrom 9.00%Jun 25, 20262 filingsJun 25, 2026SEC
ETONEton Pharmaceuticals, Inc.13G/A7.70%1.98M shares–Dec 9, 20242 filingsFeb 14, 2025SEC
ORICOric Pharmaceuticals, Inc.13G6.90%6.73M shares–Feb 16, 20216 filingsAug 5, 2025SEC
ANROAlto Neuroscience, Inc.13G5.80%2.23M sharesNewJul 20, 20261 filingJul 20, 2026SEC

Latest filings

230 filings on file made by EcoR1 Capital, LLC or listing it as a reporting person; the latest 20 are shown.

Schedule 13D and 13G filings by EcoR1 Capital, LLC
CompanyFiled (ET)FormStakeChangeEvent dateFiling
MREOMereo BioPharma Group plcAug 14, 202612:57 PM ET13G/A0.60%5.00M shares−7.80 ppfrom 8.40%Below 5%Jun 30, 2026SEC
ANROAlto Neuroscience, Inc.Jul 20, 20265:10 PM ET13G5.80%2.23M sharesNewJul 13, 2026SEC
FULCFulcrum Therapeutics, Inc.Jun 25, 20266:10 PM ET13G9.00%6.00M shares0.00 ppfrom 9.00%Jun 17, 2026SEC
FULCFulcrum Therapeutics, Inc.Jun 25, 20265:51 PM ET13G9.00%6.00M sharesNewJun 17, 2026SEC
ELOXEloxx Pharmaceuticals, Inc.Jun 16, 20267:10 PM ET13G9.90%403.6K sharesNewJun 9, 2026SEC
IBIOiBio, Inc.May 15, 20262:26 PM ET13G/A4.60%1.58M shares−5.30 ppfrom 9.90%Below 5%Mar 31, 2026SEC
MREOMereo BioPharma Group plcMay 15, 20262:25 PM ET13G/A8.40%66.8M shares−1.00 ppfrom 9.40%Mar 31, 2026SEC
XNCRXencor IncMay 15, 20262:24 PM ET13G/A2.90%2.18M shares−3.50 ppfrom 6.40%Below 5%Mar 31, 2026SEC
VYGRVoyager Therapeutics, Inc.May 15, 20262:16 PM ET13G/A0.00%0 shares−6.80 ppfrom 6.80%Below 5%Mar 31, 2026SEC
ATRAAtara Biotherapeutics, Inc.May 7, 20267:26 PM ET13G/A17.40%1.55M shares+7.50 ppfrom 9.90%May 7, 2026SEC
TRAXFirst Tracks Biotherapeutics, Inc.Apr 22, 20265:09 PM ET13G9.10%3.17M sharesNewApr 20, 2026SEC
QUREuniQure N.V.Feb 17, 20266:34 PM ET13G/A0.00%0 shares−7.50 ppfrom 7.50%Below 5%Dec 31, 2025SEC
TNGXTango Therapeutics, Inc.Feb 17, 20266:29 PM ET13G/A0.00%0 shares−9.90 ppfrom 9.90%Below 5%Dec 31, 2025SEC
XNCRXencor IncFeb 17, 20266:24 PM ET13G/A6.40%4.64M shares–Dec 31, 2025SEC
VYGRVoyager Therapeutics, Inc.Feb 17, 20266:21 PM ET13G/A6.80%4.00M shares0.00 ppfrom 6.80%Dec 31, 2025SEC
AKTSAktis Oncology, Inc.Jan 20, 20262:01 PM ET13D9.10%4.86M sharesNewJan 12, 2026SEC
MREOMereo BioPharma Group plcJan 9, 20265:24 PM ET13G9.40%74.5M sharesNewJan 2, 2026SEC
IBIOiBio, Inc.Dec 17, 20255:42 PM ET13G9.90%2.23M sharesNewDec 10, 2025SEC
ZYMEZymeworks Inc.Nov 19, 20255:39 PM ET13D/A30.70%23.0M shares0.00 ppfrom 30.70%Nov 16, 2025SEC
HLVXHilleVax, Inc.Nov 14, 20254:19 PM ET13G/A0.00%0 shares−5.80 ppfrom 5.80%Below 5%Sep 30, 2025SEC