Atlas Venture Life Science Advisors, LLC

In its 13F for Q3 2025 (holdings as of September 30, 2025, filed November 13, 2025), Atlas Venture Life Science Advisors, LLC reported 9 stock positions worth $752.6 million. Its top holding was Kymera Therapeutics (KYMR) at 36.8% of the portfolio, followed by Disc Medicine (IRON, 18.8%) and Dyne Therapeutics (DYN, 15.3%). Compared with Q2 2025, it opened 1 new position, sold out of 3 and reduced 3. The biggest buy was a new position in Imagenebio (IMA) and the biggest sale an exit from Third Harmonic Bio (THRD).

Most Recent 13F
Q2 2026
Location
CAMBRIDGE, MA
CIK
0001917529
Portfolio Value
$752.6M (Q3 2025)
SEC Filing
0001104659-25-111321 ↗ filed Nov 13, 2025

Holdings Value

0$500.0M$1.0B$1.5B Q1 2024: $1.1B Q1 2024 Q2 2024: $949.6M Q2 2024 Q3 2024: $1.1B Q3 2024 Q4 2024: $819.7M Q4 2024 Q1 2025: $521.8M Q1 2025 Q2 2025: $662.4M Q2 2025 Q3 2025: $752.6M $752.6M Q3 2025 Q4 2025: $865.2M Q4 2025 Q1 2026: $790.0M Q1 2026 Q2 2026: $881.3M Q2 2026

Holdings 9 stocks · $752.6M
KYMR Kymera Therapeutics Inc. 36.82% 4,896,462 $277.1M No change
IRON Disc Medicine Inc. 18.81% 2,142,617 $141.6M Reduce -10.1%
DYN Dyne Therapeutics Inc. 15.35% 9,130,465 $115.5M No change
SION Sionna Therapeutics Inc. 14.13% 3,615,527 $106.3M Reduce -2.1%
KRRO Korro Bio Inc. 7.24% 1,137,149 $54.5M No change
DAWN Day One Biopharmaceuticals I 6.02% 6,430,257 $45.3M No change
GBIO Generation Bio Co. 0.67% 827,946 $5.1M Reduce -90.0%
QTTB Q32 Bio Inc. 0.55% 2,092,106 $4.1M No change
IMA Imagenebio Inc. 0.41% 377,814 $3.1M New

Portfolio Sells Q2 2025 → Q3 2025
THRD Third Harmonic Bio Inc. Sold out 0.00% −8.53
VIGL Vigil Neuroscience Inc. Sold out 0.00% −7.01
IKENA ONCOLOGY INC Sold out 0.00% −1.02
IRON Disc Medicine Inc. Reduce -10.1% 18.81% −0.25
GBIO Generation Bio Co. Reduce -90.0% 0.67% +0.27
SION Sionna Therapeutics Inc. Reduce -2.1% 14.13% +4.45

Portfolio Buys Q2 2025 → Q3 2025
IMA Imagenebio Inc. New 0.41% +0.41

All Filings

QuarterPositions13F Reported ValueTop Holdings
Q2 2026 7$881.3MKYMR, DYN, SION, KLRA, IRON
Q1 2026 6$790.0MKYMR, DYN, SION, IRON, QTTB
Q4 2025 8$865.2MKYMR, DYN, SION, IRON, DAWN
Q3 2025 9$752.6MKYMR, IRON, DYN, SION, KRRO
Q2 2025 11$662.4MKYMR, IRON, DYN, SION, THRD
Q1 2025 13$521.8MKYMR, IRON, DYN, DAWN, SION
Q4 2024 13$819.7MKYMR, DYN, IRON, THRD, DAWN
Q3 2024 14$1.1BDYN, KYMR, THRD, IRON, QTTB
Q2 2024 15$949.6MDYN, KYMR, THRD, IRON, DAWN
Q1 2024 16$1.1BDYN, KYMR, IRON, DAWN, THRD