Skip to content
Disclosery

EcoR1 Capital, LLC

Follow

13F filer, CIK 1587114, San Francisco, CA

EcoR1 Capital, LLC reported $2,356,318,840 across 30 holdings for the quarter ended 2026-03-31, in a 13F-HR filed 2026-05-15. Its ten largest share positions make up 89.52% of the portfolio.

Filed (acceptance time not in the bulk data set), ingested 13F-HR 0000935836-26-000270

Period
2026-03-31
Reported value
$2.36B
Holdings
30
Top 10 weight
89.52%
New
11
Sold out
11

Largest buys vs the previous quarter

SecurityShares changeApprox. value
CNTAadded+2,885,000$115M
AKTSnew+4,824,469$86.3M
CGONadded+330,000$22.3M
RLAYnew+1,904,762$19M
ERASnew+900,000$14.6M

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.

Largest sells vs the previous quarter

SecurityShares changeApprox. value
IMNMexited-2,855,590-$61.3M
MBXreduced-1,346,604-$40.2M
GPCRexited-334,380-$23.3M
PCVXexited-450,000-$20.8M
AQSTexited-2,625,000-$17M

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, Q1 2026

Share positions as resolved from 13F-HR 0000935836-26-000270, largest first. % of portfolio is the value over $2,339,872,410, 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; 2024Q2: restricted; 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 22,970,388$575M24.58%0Timeline
ANABANAPTYSBIO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 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 7,880,094$437M18.68%0Timeline
JAZZJAZZ PHARMACEUTICALS PLCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 1,706,469 shares; 2024Q4: 1,706,469 shares; 2025Q1: 1,706,469 shares; 2025Q2: 1,706,469 shares; 2025Q3: 1,706,469 shares; 2025Q4: 1,706,469 shares; 2026Q1: 1,706,469 shares 1,706,469$323M13.79%0Timeline
CNTACENTESSA PHARMACEUTICALS PLCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 3,223,851 shares; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: 550,000 shares; 2025Q4: 3,115,000 shares; 2026Q1: 6,000,000 shares 6,000,000$238M10.19%+2,885,000Timeline
CRNXCRINETICS PHARMACEUTICALS INQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 4,288,120 shares; 2024Q4: 4,288,120 shares; 2025Q1: 4,288,120 shares; 2025Q2: 4,288,120 shares; 2025Q3: 4,288,120 shares; 2025Q4: 4,288,120 shares; 2026Q1: 4,288,120 shares 4,288,120$156M6.66%0Timeline
AKTSAKTIS ONCOLOGY INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 4,824,469 shares 4,824,469$86.3M3.69%newTimeline
ORICORIC PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 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 6,728,116$85.2M3.64%0Timeline
CGONCG ONCOLOGY INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 772,000 shares; 2026Q1: 1,102,000 shares 1,102,000$74.6M3.19%+330,000Timeline
CRSPCRISPR THERAPEUTICS AGQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 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 1,389,276$66.1M2.82%0Timeline
ETONETON PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 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 2,171,938$53.6M2.29%+141,394Timeline
LKFTLAKEFRONT BIOTHERAPEUTICS NVQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 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 1,667,119$50M2.14%0Timeline
XNCRXENCOR INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 5,330,416 shares; 2024Q4: 6,144,767 shares; 2025Q1: 6,144,767 shares; 2025Q2: 6,144,767 shares; 2025Q3: 6,144,767 shares; 2025Q4: 3,251,112 shares; 2026Q1: 2,183,000 shares 2,183,000$26.3M1.13%-1,068,112Timeline
NGNENEUROGENE INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 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 1,271,342$25.6M1.1%0Timeline
BBOTBRIDGEBIO ONCOLOGY THERAPEUTQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 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 2,823,126$25.3M1.08%0Timeline
MBXMBX BIOSCIENCES INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 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 777,000$23.2M0.99%-1,346,604Timeline
RLAYRELAY THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 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 1,904,762$19M0.81%newTimeline
ZBIOZENAS BIOPHARMA INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 789,500 shares; 2026Q1: 789,500 shares 789,500$15.4M0.66%0Timeline
ERASERASCA INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 900,000 shares 900,000$14.6M0.62%newTimeline
EIKNEIKON THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 732,606 shares 732,606$7.75M0.33%newTimeline
REPLREPLIMUNE GROUP INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: 850,341 shares; 2024Q4: 850,341 shares; 2025Q1: 850,341 shares; 2025Q2: 850,341 shares; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 1,000,000 shares 1,000,000$7.65M0.33%newTimeline
ZURAZURA BIO LTDQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 1,179,715 shares 1,179,715$7.02M0.3%newTimeline
PHATPHATHOM PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 625,000 shares 625,000$6.94M0.3%newTimeline
MREOMEREO BIOPHARMA GROUP PLCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 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 13,368,855$4.41M0.19%+5,512,389Timeline
STOKSTOKE THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 100,000 shares 100,000$3.26M0.14%newTimeline
PRLDPRELUDE THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 947,049 shares 947,049$3.24M0.14%newTimeline
IBIOIBIO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 2,228,000 shares; 2026Q1: 1,583,000 shares 1,583,000$3.01M0.13%-645,000Timeline
HLXCHELIX ACQUISITION CORP IIIQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 200,000 shares 200,000$2.03M0.09%newTimeline
ATRAATARA BIOTHERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 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 99,593$471K0.02%-473,590Timeline
SRZNWSURROZEN INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q2: restricted; 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 4,444$129K0Value about 1,000 times the price other filers imply, kept as filed and left out of ratios.Timeline

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
CNTACENTESSA PHARMACEUTICALS PLC SPONSORED ADScall410,800$16.3Mnew

Sold out in Q1 2026

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

SecurityShares beforeValue beforeType
IMNMIMMUNOME INC2,855,590$61.3Mshares
GPCRSTRUCTURE THERAPEUTICS INC334,380$23.3Mshares
PCVXVAXCYTE INC450,000$20.8Mshares
AQSTAQUESTIVE THERAPEUTICS INC2,625,000$17Mshares
VYGRVOYAGER THERAPEUTICS INC4,002,847$15.7Mshares
CGONCG ONCOLOGY INC292,800$12.2Mcall
MNKDMANNKIND CORP1,660,000$9.41Mshares
NUVATION BIO INCNUVATION BIO INC963,333$8.63Mshares
EOLSEVOLUS INC675,000$4.49Mshares
CAMPCAMP4 THERAPEUTICS CORP325,000$1.99Mshares
XNCRXENCOR INC67,500$1.03Mcall

How Q1 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 0000935836-26-000270 base2026-05-15acceptance time not in the bulk data set