AVLSA
SION

Atlas Venture Life Science Advisors’s Sionna Therapeutics SION Stock Holding History

Atlas Venture Life Science Advisors’s Portfolio SION Stock Details SION Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2026
Q2 		$132M Hold
2,995,602
– – 14.95% 3
2026
Q1 		$120M Hold
2,995,602
– – 15.2% 3
2025
Q4 		$123M Sell
2,995,602
-619,925
-17% -$23.5M 14.24% 3
2025
Q3 		$106M Sell
3,615,527
-78,493
-2% -$1.71M 14.13% 4
2025
Q2 		$64.1M Hold
3,694,020
– – 9.68% 4
2025
Q1 		$38.6M Buy
+3,694,020
New +$60.4M 7.41% 5

Other funds holding SION

RCM
RA Capital Management Boston, Massachusetts $11.5B AUM 168.77% 1-Year Est. Return
TGA
TPG GP A Fort Worth, Texas $5B AUM 58.56% 1-Year Est. Return
Viking Global Investors
Viking Global Investors Stamford, Connecticut $35.1B AUM 21.36% 1-Year Est. Return
O
OrbiMed New York $5.4B AUM 163.13% 1-Year Est. Return
ES
Enavate Sciences Menlo Park, California $345M AUM 134.64% 1-Year Est. Return
Adage Capital Partners
Adage Capital Partners Boston, Massachusetts $71.3B AUM 56.8% 1-Year Est. Return
BlackRock
BlackRock New York $6.73T AUM 46.02% 1-Year Est. Return
JP Morgan Chase
JP Morgan Chase New York $1.81T AUM 41.13% 1-Year Est. Return
Jennison Associates
Jennison Associates New York $167B AUM 44.17% 1-Year Est. Return
Citadel Advisors
Citadel Advisors Miami, Florida $875B AUM 40.89% 1-Year Est. Return

Atlas Venture Life Science Advisors's SION Position: Q2 2026 in Review

Atlas Venture Life Science Advisors held its Sionna Therapeutics (SION) position steady in Q2 2026 at 2,995,602 shares worth $132M. The position accounts for 14.95% of the portfolio, ranked #3.

Atlas Venture Life Science Advisors first reported a position in SION in Q1 2025 and has held it in 6 quarters since. 147 funds tracked by Wall St. Rank hold SION as of Q2 2026.

  • Atlas Venture Life Science Advisors held 2,995,602 shares of Sionna Therapeutics worth $132M as of Q2 2026.
  • Atlas Venture Life Science Advisors left its Sionna Therapeutics share count unchanged in Q2 2026.
  • Sionna Therapeutics made up 14.95% of Atlas Venture Life Science Advisors's portfolio in Q2 2026, its #3 holding.
  • Atlas Venture Life Science Advisors first reported a position in Sionna Therapeutics in Q1 2025 and has held it in 6 quarters since.
  • 147 funds tracked by Wall St. Rank held Sionna Therapeutics as of Q2 2026.

Based on Atlas Venture Life Science Advisors's 13F filing for Q2 2026, filed 13 Aug 2026.