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Atlas Venture Life Science Advisors, LLC

SEC CIK
0001917529
Latest filing
Aug 13, 2026

The latest 13F from Atlas Venture Life Science Advisors, LLC covers Q2 2026 (filed Aug 13, 2026): 7 long positions worth $881.3M. The top 10 holdings make up 100.0% of the portfolio, and the largest is Kymera Therapeutics, Inc. (KYMR) at 37.1%. Livermore has 19 filings on Form 13F from this institution, going back to Q4 2021.

What changed in Q2 2026

Share counts compared with Q1 2026: how many positions were new, added to, reduced or sold out, and the biggest buys and sells. Dollar amounts are estimated at the quarter-end prices implied by the filing.

Full comparison
New
1
Est. +$113.9M
Added
1
Est. +$7.96M
Reduced
3
Est. −$252.5M
Sold out
0

Top 5 holdings

Share of this quarter's portfolio value

  1. KYMRKymera Therapeutics, Inc.
    37.1%$326.5MHistory
  2. DYNDyne Therapeutics, Inc.
    17.1%$151.0MHistory
  3. SIONSionna Therapeutics, Inc.
    15.0%$131.8MHistory
  4. KLRAKailera Therapeutics, Inc.
    12.9%$113.9MHistory
  5. IRONDisc Medicine, Inc.
    12.6%$110.7MHistory

Share of portfolio

Top 5 holdings and the other 2 positions, by share of portfolio value

  1. KYMR37.1%
  2. DYN17.1%
  3. SION15.0%
  4. KLRA12.9%
  5. IRON12.6%
  6. Other 2 positions5.4%

Biggest buys

New and added positions, by estimated amount bought

  1. KLRAKailera Therapeutics, Inc.
    +$113.9MNewHistory
  2. QTTBQ32 Bio Inc.
    +$7.96MAddedHistory

Largest weight increases

New and added positions, by percentage points of the portfolio gained

  1. KLRAKailera Therapeutics, Inc.
    +12.93 pp0.0% → 12.9%History
  2. QTTBQ32 Bio Inc.
    +2.23 pp1.7% → 3.9%History

Biggest sells

Reduced and sold-out positions, by estimated amount sold

  1. KYMRKymera Therapeutics, Inc.
    −$198.4MReducedHistory
  2. DYNDyne Therapeutics, Inc.
    −$51.8MReducedHistory
  3. KRROKorro Bio, Inc.
    −$2.30MReducedHistory

Largest weight decreases

Reduced and sold-out positions, by percentage points of the portfolio lost

  1. KYMRKymera Therapeutics, Inc.
    −11.21 pp48.3% → 37.1%History
  2. DYNDyne Therapeutics, Inc.
    −3.82 pp21.0% → 17.1%History
  3. KRROKorro Bio, Inc.
    −0.19 pp1.6% → 1.4%History

Metrics

13F metrics for Q2 2026, computed only from the numbers in the filings. Definitions below.

Portfolio value
$881.3M
+$91.3M (+11.6%) vs. prior quarter
Positions
7
+1 vs. prior quarter
Top 10 concentration
100.0%
Top 10 as share of value
Turnover
14.6%
Q2 2026, one quarter
Average holding period
13.8 quarters
Weighted by value

How these are calculated

  • Portfolio value: the market value of all long positions in the 13F, as reported at quarter end, excluding options.
  • Top 10 concentration: the combined value of the 10 largest positions as a share of portfolio value.
  • Turnover: the smaller of this quarter's estimated purchases and estimated sales, divided by the average of this and last quarter's portfolio value. Estimates multiply the change in shares by the quarter-end price implied by the filing (market value divided by shares); new positions use this quarter's value and sold-out positions last quarter's. Only positions reported in shares count, and it is not calculated when the previous quarter was not filed.
  • Average holding period: how many consecutive quarters each current position has been held (including this one; a quarter without the position or without a filing starts the count over), weighted by this quarter's value. Counting starts with the first 13F in Livermore (Q4 2021), so positions held before then are understated.

13F filings by quarter

19 quarters, going back to Q4 2021. Bars show each quarter's 13F portfolio value; quarters without a filing are left blank.

Peak $1.09B (Q4 2021)

Q4 2021: $1.09BQ1 2022: $791.0MQ2 2022: $598.2MQ3 2022: $906.2MQ4 2022: $830.2MQ1 2023: $738.6MQ2 2023: $803.6MQ3 2023: $645.6MQ4 2023: $839.8MQ1 2024: $1.08BQ2 2024: $949.6MQ3 2024: $1.08BQ4 2024: $819.7MQ1 2025: $521.8MQ2 2025: $662.4MQ3 2025: $752.6MQ4 2025: $865.2MQ1 2026: $790.0MQ2 2026: $881.3M
Q4 2021Q2 2026
13F filings of Atlas Venture Life Science Advisors, LLC by quarter
QuarterFiledPositionsValueTop 3 holdingsChangesFiling
Q2 2026Aug 13, 20267$881.3MKYMRDYNSIONvs. Q1 2026SEC
Q1 2026May 14, 20266$790.0MKYMRDYNSIONvs. Q4 2025SEC
Q4 2025Feb 13, 20268$865.2MKYMRDYNSIONvs. Q3 2025SEC
Q3 2025Nov 13, 20259$752.6MKYMRIRONDYNvs. Q2 2025SEC
Q2 2025Aug 12, 202511$662.4MKYMRIRONDYNvs. Q1 2025SEC
Q1 2025May 14, 202513$521.8MKYMRIRONDYNvs. Q4 2024SEC
Q4 2024Feb 6, 202513$819.7MKYMRDYNIRONvs. Q3 2024SEC
Q3 2024Nov 13, 202414$1.08BDYNKYMRTHRDvs. Q2 2024SEC
Q2 2024Aug 9, 202415$949.6MDYNKYMRTHRDvs. Q1 2024SEC
Q1 2024May 6, 202416$1.08BDYNKYMRIRONvs. Q4 2023SEC
Q4 2023Feb 9, 202416$839.8MKYMRIRONDYNvs. Q3 2023SEC
Q3 2023Nov 13, 202315$645.6MIRONDAWNDYNvs. Q2 2023SEC
Q2 2023Aug 11, 202315$803.6MIRONKYMRDYNvs. Q1 2023SEC
Q1 2023May 15, 202316$738.6MKYMRDYNDAWNvs. Q4 2022SEC
Q4 2022Feb 14, 202317$830.2MDAWNKYMRDYNvs. Q3 2022SEC
Q3 2022Nov 9, 202217$906.2MTHRDDAWNKYMRvs. Q2 2022SEC
Q2 2022Aug 3, 202216$598.2MDAWNKYMRDYNvs. Q1 2022SEC
Q1 2022May 16, 202217$791.0MKYMRDYNDAWNvs. Q4 2021SEC
Q4 2021May 16, 202216$1.09BKYMRDAWNDYN–SEC