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EcoR1 Capital, LLC

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13F filer, CIK 1587114, San Francisco, CA

EcoR1 Capital, LLC reported $2,204,008,593 across 30 holdings for the quarter ended 2025-12-31, in a 13F-HR filed 2026-02-17. Its ten largest share positions make up 85.14% of the portfolio.

Filed (acceptance time not in the bulk data set), ingested 13F-HR 0000935836-26-000101

Period
2025-12-31
Reported value
$2.2B
Holdings
30
Top 10 weight
85.14%
New
11
Sold out
11

Largest buys vs the previous quarter

SecurityShares changeApprox. value
CNTAadded+2,565,000$64.2M
CGONnew+772,000$32.1M
ZBIOnew+789,500$28.7M
GPCRnew+334,380$23.3M
PCVXnew+450,000$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
QUREexited-3,988,971-$233M
TNGXexited-10,630,736-$89.3M
APLSexited-3,447,156-$78M
XNCRreduced-2,893,655-$44.3M
MDGLexited-75,000-$34.4M

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, Q4 2025

Share positions as resolved from 13F-HR 0000935836-26-000101, largest first. % of portfolio is the value over $2,190,818,112, 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; 2024Q1: restricted; 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 22,970,388$605M27.61%0Timeline
ANABANAPTYSBIO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 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 7,880,094$382M17.44%0Timeline
JAZZJAZZ PHARMACEUTICALS PLCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 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 1,706,469$290M13.24%0Timeline
CRNXCRINETICS PHARMACEUTICALS INQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 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 4,288,120$200M9.11%0Timeline
CNTACENTESSA PHARMACEUTICALS PLCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 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 3,115,000$77.9M3.56%+2,565,000Timeline
CRSPCRISPR THERAPEUTICS AGQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 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 1,389,276$72.9M3.33%0Timeline
MBXMBX BIOSCIENCES INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 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 2,123,604$67M3.06%0Timeline
IMNMIMMUNOME INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 3,879,415 shares; 2024Q4: 3,879,415 shares; 2025Q1: 4,079,415 shares; 2025Q2: 4,079,415 shares; 2025Q3: 4,079,415 shares; 2025Q4: 2,855,590 shares 2,855,590$61.3M2.8%-1,223,825Timeline
ORICORIC PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 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 6,728,116$55M2.51%0Timeline
LKFTLAKEFRONT BIOTHERAPEUTICS NVQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 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 1,667,119$54.5M2.49%0Timeline
XNCRXENCOR INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 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 3,251,112$49.8M2.27%-2,893,655Timeline
BBOTBRIDGEBIO ONCOLOGY THERAPEUTQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: 2,823,126 shares; 2025Q4: 2,823,126 shares 2,823,126$35.3M1.61%0Timeline
ETONETON PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 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 2,030,544$34.3M1.57%0Timeline
CGONCG ONCOLOGY INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 772,000 shares 772,000$32.1M1.46%newTimeline
ZBIOZENAS BIOPHARMA INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 789,500 shares 789,500$28.7M1.31%newTimeline
NGNENEUROGENE INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 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 1,271,342$26.2M1.2%0Timeline
GPCRSTRUCTURE THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 334,380 shares 334,380$23.3M1.06%newTimeline
PCVXVAXCYTE INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 352,464 shares; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 450,000 shares 450,000$20.8M0.95%newTimeline
AQSTAQUESTIVE THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: 2,625,000 shares; 2025Q4: 2,625,000 shares 2,625,000$17M0.77%0Timeline
VYGRVOYAGER THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 3,917,546 shares; 2024Q4: 3,917,546 shares; 2025Q1: 3,917,546 shares; 2025Q2: 3,917,546 shares; 2025Q3: 670,303 shares; 2025Q4: 4,002,847 shares 4,002,847$15.7M0.72%+3,332,544Timeline
ATRAATARA BIOTHERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 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 573,183$10.4M0.47%0Timeline
MNKDMANNKIND CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 1,660,000 shares 1,660,000$9.41M0.43%newTimeline
NUVATION BIO INCNUVATION BIO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 963,333 shares; 2024Q4: 963,333 shares; 2025Q1: 963,333 shares; 2025Q2: 963,333 shares; 2025Q3: 963,333 shares; 2025Q4: 963,333 shares 963,333$8.63M0.39%0
EOLSEVOLUS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 675,000 shares 675,000$4.49M0.2%newTimeline
IBIOIBIO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 2,228,000 shares 2,228,000$4.3M0.2%newTimeline
MREOMEREO BIOPHARMA GROUP PLCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 7,856,466 shares 7,856,466$3.27M0.15%newTimeline
CAMPCAMP4 THERAPEUTICS CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 325,000 shares 325,000$1.99M0.09%newTimeline
SRZNWSURROZEN INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 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 4,444$100K<0.01%-62,221Timeline

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 STOCKcall292,800$12.2Mnew
XNCRXENCOR INC COMMON STOCKcall67,500$1.03Mnew

Sold out in Q4 2025

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

SecurityShares beforeValue beforeType
QUREUNIQURE NV3,988,971$233Mshares
TNGXTANGO THERAPEUTICS INC10,630,736$89.3Mshares
APLSAPELLIS PHARMACEUTICALS INC3,447,156$78Mshares
MDGLMADRIGAL PHARMACEUTICALS INC75,000$34.4Mshares
RNAMAVIDITY BIOSCIENCES INC765,000$33.3Mshares
ALKSALKERMES PLC500,000$15Mshares
MTSRMETSERA INC271,529$14.2Mshares
PRMEPRIME MEDICINE INC1,543,326$8.55Mshares
KURAKURA ONCOLOGY INC872,500$7.72Mshares
PEPGPEPGEN INC800,000$3.7Mshares
CMPSCOMPASS PATHWAYS PLC265,137$1.52Mshares

How Q4 2025 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 0000935836-26-000101 base2026-02-17acceptance time not in the bulk data set