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EcoR1 Capital, LLC

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13F filer, CIK 1587114, San Francisco, CA

EcoR1 Capital, LLC reported $2,056,733,459 across 33 holdings for the quarter ended 2026-06-30, in a 13F-HR filed 2026-08-14. Its ten largest share positions make up 88.02% of the portfolio.

Filed (acceptance time not in the bulk data set), ingested 13F-HR 0000935836-26-000415

Period
2026-06-30
Reported value
$2.06B
Holdings
33
Top 10 weight
88.02%
New
11
Sold out
8

Largest buys vs the previous quarter

SecurityShares changeApprox. value
TRAXnew+3,174,519$63.9M
CGONadded+392,300$27.9M
FULCnew+6,549,866$24M
LEGNnew+800,000$23.1M
STOKadded+635,000$20.8M

Ranked by the share change valued at this quarter's implied price (value over shares in the 13F). A position sold out is valued at the previous quarter's price, its last report.

Largest sells vs the previous quarter

SecurityShares changeApprox. value
JAZZexited-1,706,469-$323M
CNTAexited-6,000,000-$238M
CRNXexited-4,288,120-$156M
XNCRexited-2,183,000-$26.3M
RLAYreduced-1,206,814-$22.6M

Ranked by the share change valued at this quarter's implied price (value over shares in the 13F). A position sold out is valued at the previous quarter's price, its last report.

Holdings, Q2 2026

Share positions as resolved from 13F-HR 0000935836-26-000415, largest first. % of portfolio is the value over $2,016,754,212, the sum of the share positions whose value is usable for ratios (method).

SecurityHistorySharesValue% of portfolioChangeLatest eventTimeline
ZYMEZYMEWORKS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: 13,437,473 shares; 2024Q4: 15,028,079 shares; 2025Q1: 17,259,548 shares; 2025Q2: 22,970,388 shares; 2025Q3: 22,970,388 shares; 2025Q4: 22,970,388 shares; 2026Q1: 22,970,388 shares; 2026Q2: 22,970,388 shares 22,970,388$600M29.77%0Timeline
ANABANAPTYSBIO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: 7,794,996 shares; 2024Q4: 7,873,448 shares; 2025Q1: 7,880,094 shares; 2025Q2: 7,880,094 shares; 2025Q3: 7,880,094 shares; 2025Q4: 7,880,094 shares; 2026Q1: 7,880,094 shares; 2026Q2: 7,880,094 shares 7,880,094$532M26.37%0Timeline
AKTSAKTIS ONCOLOGY INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 4,824,469 shares; 2026Q2: 4,824,469 shares 4,824,469$155M7.71%0Timeline
CGONCG ONCOLOGY INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 772,000 shares; 2026Q1: 1,102,000 shares; 2026Q2: 1,494,300 shares 1,494,300$106M5.26%+392,300Timeline
ETONETON PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: 566,075 shares; 2024Q4: 1,829,603 shares; 2025Q1: 1,939,288 shares; 2025Q2: 2,030,544 shares; 2025Q3: 2,030,544 shares; 2025Q4: 2,030,544 shares; 2026Q1: 2,171,938 shares; 2026Q2: 2,171,938 shares 2,171,938$78.6M3.9%0Timeline
CRSPCRISPR THERAPEUTICS AGQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: 1,389,276 shares; 2024Q4: 1,389,276 shares; 2025Q1: 1,389,276 shares; 2025Q2: 1,389,276 shares; 2025Q3: 1,389,276 shares; 2025Q4: 1,389,276 shares; 2026Q1: 1,389,276 shares; 2026Q2: 1,389,276 shares 1,389,276$75.8M3.76%0Timeline
ORICORIC PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: 3,418,068 shares; 2024Q4: 3,418,068 shares; 2025Q1: 3,418,068 shares; 2025Q2: 1,618,068 shares; 2025Q3: 6,728,116 shares; 2025Q4: 6,728,116 shares; 2026Q1: 6,728,116 shares; 2026Q2: 6,728,116 shares 6,728,116$72.9M3.61%0Timeline
TRAXFIRST TRACKS BIOTHERAPEUTICSQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: not reported; 2026Q2: 3,174,519 shares 3,174,519$63.9M3.17%newTimeline
LKFTLAKEFRONT BIOTHERAPEUTICS NVQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: 155,006 shares; 2024Q4: 155,006 shares; 2025Q1: 155,006 shares; 2025Q2: 1,036,945 shares; 2025Q3: 1,667,119 shares; 2025Q4: 1,667,119 shares; 2026Q1: 1,667,119 shares; 2026Q2: 1,667,119 shares 1,667,119$50M2.48%0Timeline
NGNENEUROGENE INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: 1,271,342 shares; 2024Q4: 1,271,342 shares; 2025Q1: 1,271,342 shares; 2025Q2: 1,271,342 shares; 2025Q3: 1,271,342 shares; 2025Q4: 1,271,342 shares; 2026Q1: 1,271,342 shares; 2026Q2: 1,271,342 shares 1,271,342$40M1.98%0Timeline
STOKSTOKE THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 100,000 shares; 2026Q2: 735,000 shares 735,000$24M1.19%+635,000Timeline
FULCFULCRUM THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: not reported; 2026Q2: 6,549,866 shares 6,549,866$24M1.19%newTimeline
LEGNLEGEND BIOTECH CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: not reported; 2026Q2: 800,000 shares 800,000$23.1M1.15%newTimeline
BBOTBRIDGEBIO ONCOLOGY THERAPEUTQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: 2,823,126 shares; 2025Q4: 2,823,126 shares; 2026Q1: 2,823,126 shares; 2026Q2: 2,823,126 shares 2,823,126$21.5M1.07%0Timeline
MBXMBX BIOSCIENCES INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: 1,175,809 shares; 2024Q4: 1,259,273 shares; 2025Q1: 1,259,273 shares; 2025Q2: 1,149,794 shares; 2025Q3: 2,123,604 shares; 2025Q4: 2,123,604 shares; 2026Q1: 777,000 shares; 2026Q2: 388,500 shares 388,500$21.4M1.06%-388,500Timeline
ZBIOZENAS BIOPHARMA INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 789,500 shares; 2026Q1: 789,500 shares; 2026Q2: 789,500 shares 789,500$20M0.99%0Timeline
ATRAATARA BIOTHERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: 468,938 shares; 2024Q4: 532,134 shares; 2025Q1: 573,183 shares; 2025Q2: 573,183 shares; 2025Q3: 573,183 shares; 2025Q4: 573,183 shares; 2026Q1: 99,593 shares; 2026Q2: 1,552,000 shares 1,552,000$17.8M0.88%+1,452,407Timeline
RLAYRELAY THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: 2,500,000 shares; 2024Q4: 641,426 shares; 2025Q1: 641,426 shares; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 1,904,762 shares; 2026Q2: 697,948 shares 697,948$13.1M0.65%-1,206,814Timeline
AURAAURA BIOSCIENCES INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: not reported; 2026Q2: 1,666,667 shares 1,666,667$11.8M0.59%newTimeline
ODTXODYSSEY THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: not reported; 2026Q2: 555,555 shares 555,555$10.4M0.52%newTimeline
EIKNEIKON THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 732,606 shares; 2026Q2: 732,606 shares 732,606$9.56M0.47%0Timeline
PHVSPHARVARIS N VQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: 900,000 shares; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: not reported; 2026Q2: 235,000 shares 235,000$8.13M0.4%newTimeline
ZURAZURA BIO LTDQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 1,179,715 shares; 2026Q2: 1,179,715 shares 1,179,715$6.96M0.35%0Timeline
PHATPHATHOM PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 625,000 shares; 2026Q2: 625,000 shares 625,000$6.78M0.34%0Timeline
NRIXNURIX THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: not reported; 2026Q2: 270,000 shares 270,000$6.55M0.32%newTimeline
ERASERASCA INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 900,000 shares; 2026Q2: 330,000 shares 330,000$6.05M0.3%-570,000Timeline
ELOXELOXX PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: not reported; 2026Q2: 400,000 shares 400,000$5.55M0.28%newTimeline
AARDAARDVARK THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: not reported; 2026Q2: 396,194 shares 396,194$2.28M0.11%newTimeline
HLXCHELIX ACQUISITION CORP IIIQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 200,000 shares; 2026Q2: 200,000 shares 200,000$2.13M0.11%0Timeline
MREOMEREO BIOPHARMA GROUP PLCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 7,856,466 shares; 2026Q1: 13,368,855 shares; 2026Q2: 1,000,000 shares 1,000,000$318K0.02%-12,368,855Timeline
SRZNWSURROZEN INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: 66,665 shares; 2024Q4: 66,665 shares; 2025Q1: 66,665 shares; 2025Q2: 66,665 shares; 2025Q3: 66,665 shares; 2025Q4: 4,444 shares; 2026Q1: 4,444 shares; 2026Q2: 4,444 shares 4,444$115K0.01%0Timeline

Options

Puts and calls, as filed. The amount and value describe the underlying shares, not the option premium, so they stay out of % of portfolio (H5).

SecurityTypeAmountValueChange
CGONCG ONCOLOGY INC COMMON STOCKcall561,500$39.9Mnew
AARDAARDVARK THERAPEUTICS INC COMcall14,700$84.7Knew

Sold out in Q2 2026

Positions in the previous quarter's report that this quarter's report no longer lists.

SecurityShares beforeValue beforeType
JAZZJAZZ PHARMACEUTICALS PLC1,706,469$323Mshares
CNTACENTESSA PHARMACEUTICALS PLC6,000,000$238Mshares
CRNXCRINETICS PHARMACEUTICALS IN4,288,120$156Mshares
XNCRXENCOR INC2,183,000$26.3Mshares
CNTACENTESSA PHARMACEUTICALS PLC410,800$16.3Mcall
REPLREPLIMUNE GROUP INC1,000,000$7.65Mshares
PRLDPRELUDE THERAPEUTICS INC947,049$3.24Mshares
IBIOIBIO INC1,583,000$3.01Mshares

How Q2 2026 was built

Available 13F filings of this filer for the quarter and their roles: the base report is the latest original or restatement, NEW HOLDINGS amendments filed after it are added (method).

FilingRoleAmendmentFiledAcceptedIngested
13F-HR 0000935836-26-000415 base2026-08-14acceptance time not in the bulk data set