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Atlas Venture Life Science Advisors, LLC

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13F filer, CIK 1917529, CAMBRIDGE, MA

Atlas Venture Life Science Advisors, LLC reported $752,636,873 across 9 holdings for the quarter ended 2025-09-30, in a 13F-HR filed 2025-11-13.

Filed (acceptance time not in the bulk data set), ingested 13F-HR 0001104659-25-111321

Period
2025-09-30
Reported value
$753M
Holdings
9
Top 10 weight
100%
New
1
Sold out
3

Largest buys vs the previous quarter

SecurityShares changeApprox. value
IMAnew+377,814$3.08M

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
THRDexited-10,402,286-$56.5M
VIGIL NEUROSCIENCE INCexited-5,836,874-$46.4M
GENERATION BIO COreduced-7,451,538-$45.6M
IRONreduced-241,839-$16M
IKENA ONCOLOGY INCexited-5,018,178-$6.72M

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, Q3 2025

Share positions as resolved from 13F-HR 0001104659-25-111321, largest first. % of portfolio is the value over $752,636,873, the sum of the share positions whose value is usable for ratios (method).

SecurityHistorySharesValue% of portfolioChangeLatest eventTimeline
KYMRKYMERA THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 4,896,462 shares; 2024Q4: 4,896,462 shares; 2025Q1: 4,896,462 shares; 2025Q2: 4,896,462 shares; 2025Q3: 4,896,462 shares 4,896,462$277M36.82%0Timeline
IRONDISC MEDICINE INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 2,509,456 shares; 2024Q4: 2,509,456 shares; 2025Q1: 2,384,456 shares; 2025Q2: 2,384,456 shares; 2025Q3: 2,142,617 shares 2,142,617$142M18.81%-241,839Timeline
DYNDYNE THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 8,020,136 shares; 2024Q4: 8,019,354 shares; 2025Q1: 9,130,465 shares; 2025Q2: 9,130,465 shares; 2025Q3: 9,130,465 shares 9,130,465$116M15.35%0Timeline
SIONSIONNA THERAPEUTICS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: 3,694,020 shares; 2025Q2: 3,694,020 shares; 2025Q3: 3,615,527 shares 3,615,527$106M14.13%-78,493Timeline
KRROKORRO BIO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 1,137,149 shares; 2024Q4: 1,137,149 shares; 2025Q1: 1,137,149 shares; 2025Q2: 1,137,149 shares; 2025Q3: 1,137,149 shares 1,137,149$54.5M7.24%0Timeline
DAWNDAY ONE BIOPHARMACEUTICALS IQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 6,430,257 shares; 2024Q4: 6,430,257 shares; 2025Q1: 6,430,257 shares; 2025Q2: 6,430,257 shares; 2025Q3: 6,430,257 shares 6,430,257$45.3M6.02%0Timeline
GENERATION BIO COGENERATION BIO COQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 8,279,484 shares; 2024Q4: 8,279,484 shares; 2025Q1: 8,279,484 shares; 2025Q2: 8,279,484 shares; 2025Q3: 827,946 shares 827,946$5.07M0.67%-7,451,538
QTTBQ32 BIO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 2,092,106 shares; 2024Q4: 2,092,106 shares; 2025Q1: 2,092,106 shares; 2025Q2: 2,092,106 shares; 2025Q3: 2,092,106 shares 2,092,106$4.14M0.55%0Timeline
IMAIMAGENEBIO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: 377,814 shares 377,814$3.08M0.41%newTimeline

Sold out in Q3 2025

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

SecurityShares beforeValue beforeType
THRDTHIRD HARMONIC BIO INC10,402,286$56.5Mshares
VIGIL NEUROSCIENCE INCVIGIL NEUROSCIENCE INC5,836,874$46.4Mshares
IKENA ONCOLOGY INCIKENA ONCOLOGY INC5,018,178$6.72Mshares

How Q3 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 0001104659-25-111321 base2025-11-13acceptance time not in the bulk data set