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EcoR1 Capital, LLC

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13F filer, CIK 1587114, San Francisco, CA

EcoR1 Capital, LLC reported $1,686,022,983 across 46 holdings for the quarter ended 2025-03-31, in a 13F-HR filed 2025-05-15. Its ten largest share positions make up 80.13% of the portfolio.

Filed (acceptance time not in the bulk data set), ingested 13F-HR 0000935836-25-000338

Period
2025-03-31
Reported value
$1.69B
Holdings
46
Top 10 weight
80.13%
New
5
Sold out
18

Largest buys vs the previous quarter

SecurityShares changeApprox. value
SRPTadded+522,386$33.3M
ZYMEadded+2,231,469$26.6M
AKROnew+440,000$17.8M
BEAMnew+526,685$10.3M
QUREadded+588,971$6.24M

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
ARVNexited-6,726,491-$129M
SPRINGWORKS THERAPEUTICS INCexited-1,560,000-$56.4M
THRDexited-3,182,444-$32.7M
NMRAexited-2,071,450-$22M
CARGO THERAPEUTICS INC COMexited-1,470,000-$21.2M

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 2025

Share positions as resolved from 13F-HR 0000935836-25-000338, largest first. % of portfolio is the value over $1,683,159,179, the sum of the share positions whose value is usable for ratios (method).

SecurityHistorySharesValue% of portfolioChangeLatest eventTimeline
APLSAPELLIS PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 11,890,843 shares; 2024Q4: 11,890,843 shares; 2025Q1: 11,895,808 shares 11,895,808$260M15.46%+4,965Timeline
JAZZJAZZ PHARMACEUTICALS PLCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 1,706,469 shares; 2024Q4: 1,706,469 shares; 2025Q1: 1,706,469 shares 1,706,469$212M12.59%0Timeline
ZYMEZYMEWORKS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 13,437,473 shares; 2024Q4: 15,028,079 shares; 2025Q1: 17,259,548 shares 17,259,548$206M12.21%+2,231,469Timeline
ANABANAPTYSBIO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 7,794,996 shares; 2024Q4: 7,873,448 shares; 2025Q1: 7,880,094 shares 7,880,094$146M8.7%+6,646Timeline
CRNXCRINETICS PHARMACEUTICALS INQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 4,288,120 shares; 2024Q4: 4,288,120 shares; 2025Q1: 4,288,120 shares 4,288,120$144M8.54%0Timeline
PRTAPROTHENA CORP PLCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 11,584,280 shares; 2024Q4: 11,584,280 shares; 2025Q1: 11,584,280 shares 11,584,280$143M8.52%0Timeline
SRPTSAREPTA THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: 770,000 shares; 2025Q1: 1,292,386 shares 1,292,386$82.5M4.9%+522,386Timeline
XNCRXENCOR INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 5,330,416 shares; 2024Q4: 6,144,767 shares; 2025Q1: 6,144,767 shares 6,144,767$65.4M3.88%0Timeline
CRSPCRISPR THERAPEUTICS AGQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 1,389,276 shares; 2024Q4: 1,389,276 shares; 2025Q1: 1,389,276 shares 1,389,276$47.3M2.81%0Timeline
QUREUNIQURE NVQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: 3,400,000 shares; 2025Q1: 3,988,971 shares 3,988,971$42.3M2.51%+588,971Timeline
JANXJANUX THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 1,469,818 shares; 2024Q4: 1,469,818 shares; 2025Q1: 1,469,818 shares 1,469,818$39.7M2.36%0Timeline
IMNMIMMUNOME INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 3,879,415 shares; 2024Q4: 3,879,415 shares; 2025Q1: 4,079,415 shares 4,079,415$27.5M1.63%+200,000Timeline
ETONETON PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 566,075 shares; 2024Q4: 1,829,603 shares; 2025Q1: 1,939,288 shares 1,939,288$25.2M1.5%+109,685Timeline
MDGLMADRIGAL PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 75,000 shares; 2024Q4: 75,000 shares; 2025Q1: 75,000 shares 75,000$24.8M1.48%0Timeline
ORICORIC PHARMACEUTICALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 3,418,068 shares; 2024Q4: 3,418,068 shares; 2025Q1: 3,418,068 shares 3,418,068$19.1M1.13%0Timeline
AKROAKERO THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: 440,000 shares 440,000$17.8M1.06%newTimeline
KURAKURA ONCOLOGY INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 5,806,871 shares; 2024Q4: 3,557,269 shares; 2025Q1: 2,640,298 shares 2,640,298$17.4M1.04%-916,971Timeline
TECXTECTONIC THERAPEUTIC INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 849,143 shares; 2024Q4: 849,143 shares; 2025Q1: 935,121 shares 935,121$16.6M0.98%+85,978Timeline
RNAMAVIDITY BIOSCIENCES INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 757,576 shares; 2024Q4: 557,576 shares; 2025Q1: 557,576 shares 557,576$16.5M0.98%0Timeline
NGNENEUROGENE INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 1,271,342 shares; 2024Q4: 1,271,342 shares; 2025Q1: 1,271,342 shares 1,271,342$14.9M0.88%0Timeline
TNGXTANGO THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 13,330,736 shares; 2024Q4: 10,630,736 shares; 2025Q1: 10,630,736 shares 10,630,736$14.6M0.87%0Timeline
VYGRVOYAGER THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 3,917,546 shares; 2024Q4: 3,917,546 shares; 2025Q1: 3,917,546 shares 3,917,546$13.2M0.79%0Timeline
BEAMBEAM THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: 526,685 shares 526,685$10.3M0.61%newTimeline
MBXMBX BIOSCIENCES INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 1,175,809 shares; 2024Q4: 1,259,273 shares; 2025Q1: 1,259,273 shares 1,259,273$9.29M0.55%0Timeline
DNAGINKGO BIOWORKS HOLDINGS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: 1,743,344 shares; 2025Q1: 1,462,328 shares 1,462,328$8.34M0.5%-281,016Timeline
REPLREPLIMUNE GROUP INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 850,341 shares; 2024Q4: 850,341 shares; 2025Q1: 850,341 shares 850,341$8.29M0.49%0Timeline
BCYCBICYCLE THERAPEUTICS PLCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 910,000 shares; 2024Q4: 910,000 shares; 2025Q1: 910,000 shares 910,000$7.73M0.46%0Timeline
DAWNDAY ONE BIOPHARMACEUTICALS IQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 862,068 shares; 2024Q4: 862,068 shares; 2025Q1: 862,068 shares 862,068$6.84M0.41%0Timeline
VERVE THERAPEUTICS INCVERVE THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 1,250,000 shares; 2024Q4: 1,250,000 shares; 2025Q1: 1,250,000 shares 1,250,000$5.71M0.34%0
ADAPYADAPTIMMUNE THERAPEUTICS PLC SQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 27,404,070 shares; 2024Q4: 27,404,070 shares; 2025Q1: 27,404,070 shares 27,404,070$5.4M0.32%0Timeline
LKFTLAKEFRONT BIOTHERAPEUTICS NVQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 155,006 shares; 2024Q4: 155,006 shares; 2025Q1: 155,006 shares 155,006$3.89M0.23%0Timeline
WHWKWHITEHAWK THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 1,845,253 shares; 2024Q4: 345,253 shares; 2025Q1: 2,082,000 shares 2,082,000$3.71M0.22%+1,736,747Timeline
ATRAATARA BIOTHERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 468,938 shares; 2024Q4: 532,134 shares; 2025Q1: 573,183 shares 573,183$3.4M0.2%+41,049Timeline
SLDBSOLID BIOSCIENCES INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: 744,450 shares 744,450$2.75M0.16%newTimeline
KROSKEROS THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 187,500 shares; 2024Q4: 187,500 shares; 2025Q1: 187,500 shares 187,500$1.91M0.11%0Timeline
NUVATION BIO INCNUVATION BIO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 963,333 shares; 2024Q4: 963,333 shares; 2025Q1: 963,333 shares 963,333$1.7M0.1%0
RLAYRELAY THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 2,500,000 shares; 2024Q4: 641,426 shares; 2025Q1: 641,426 shares 641,426$1.68M0.1%0Timeline
KLRSKALARIS THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: 201,718 shares 201,718$1.62M0.1%newTimeline
PRMEPRIME MEDICINE INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 700,000 shares; 2024Q4: 700,000 shares; 2025Q1: 700,000 shares 700,000$1.39M0.08%0Timeline
MTSRMETSERA INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: 50,000 shares 50,000$1.36M0.08%newTimeline
TCRXTSCAN THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 5,000,000 shares; 2024Q4: 5,000,000 shares; 2025Q1: 662,833 shares 662,833$915K0.05%-4,337,167Timeline
SRZNWSURROZEN INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 66,665 shares; 2024Q4: 66,665 shares; 2025Q1: 66,665 shares 66,665$777K0Value about 1,000 times the price other filers imply, kept as filed and left out of ratios.Timeline
ALGSALIGOS THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 255,573 shares; 2024Q4: 255,573 shares; 2025Q1: 88,569 shares 88,569$731K0.04%-167,004Timeline
UPBUPSTREAM BIO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q2: restricted; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: 60,000 shares; 2025Q1: 60,000 shares 60,000$367K0.02%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
QUREUNIQURE NV SHScall135,000$1.43M-250,000
ETONETON PHARMACEUTICALS INC COMMON STOCKcall50,500$655K-100,900

Sold out in Q1 2025

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

SecurityShares beforeValue beforeType
PFEPFIZER INC5,000,000$133Mcall
ARVNARVINAS INC6,726,491$129Mshares
SPRINGWORKS THERAPEUTICS INCSPRINGWORKS THERAPEUTICS INC1,560,000$56.4Mshares
THRDTHIRD HARMONIC BIO INC3,182,444$32.7Mshares
NMRANEUMORA THERAPEUTICS INC.2,071,450$22Mshares
CARGO THERAPEUTICS INC COMCARGO THERAPEUTICS INC COM1,470,000$21.2Mshares
MLTXMOONLAKE IMMUNOTHERAPEUTICS332,522$18Mshares
Mersana Therapeutics IncMersana Therapeutics Inc11,328,000$16.2Mshares
KYMRKYMERA THERAPEUTICS INC350,000$14.1Mshares
DYNDYNE THERAPEUTICS INC555,644$13.1Mshares
AVIRATEA PHARMACEUTICALS INC3,341,653$11.2Mshares
FATEFATE THERAPEUTICS INC3,049,405$5.03Mshares
ALLOVIR INCALLOVIR INC408,688$3.95Mshares
DSGNDESIGN THERAPEUTICS INC426,683$2.63Mshares
GENERATION BIO COGENERATION BIO CO2,046,867$2.17Mshares
HOOKHOOKIPA PHARMA INC COM NEW388,861$782Kshares
ARTVARTIVA BIOTHERAPEUTICS INC41,453$418Kshares
GLUEMONTE ROSA THERAPEUTICS INC21,700$151Kcall

How Q1 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 0000935836-25-000338 base2025-05-15acceptance time not in the bulk data set