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
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 $9.44B AUM 157.3% 1-Year Est. Return
TGA
TPG GP A Fort Worth, Texas $3.68B AUM 14.99% 1-Year Est. Return
O
OrbiMed New York $5.05B AUM 125.28% 1-Year Est. Return
Viking Global Investors
Viking Global Investors Stamford, Connecticut $35.7B AUM 21.3% 1-Year Est. Return
ES
Enavate Sciences Menlo Park, California $352M AUM 220.14% 1-Year Est. Return
Jennison Associates
Jennison Associates New York $145B AUM 34.61% 1-Year Est. Return
JP Morgan Chase
JP Morgan Chase New York $1.56T AUM 27.86% 1-Year Est. Return
BlackRock
BlackRock New York $5.72T AUM 30.48% 1-Year Est. Return
Citadel Advisors
Citadel Advisors Miami, Florida $618B AUM 30.34% 1-Year Est. Return
VCM
Vanguard Capital Management Malvern, Pennsylvania $4.04T AUM

Atlas Venture Life Science Advisors's SION Position: Q1 2026 in Review

Atlas Venture Life Science Advisors held its Sionna Therapeutics (SION) position steady in Q1 2026 at 2,995,602 shares worth $120M. The position accounts for 15.2% of the portfolio, ranked #3.

Atlas Venture Life Science Advisors first reported a position in SION in Q1 2025 and has held it in 5 quarters since. The position peaked at $123M in Q4 2025. 122 funds tracked by Wall St. Rank hold SION as of Q1 2026.

  • Atlas Venture Life Science Advisors held 2,995,602 shares of Sionna Therapeutics worth $120M as of Q1 2026.
  • Atlas Venture Life Science Advisors left its Sionna Therapeutics share count unchanged in Q1 2026.
  • Sionna Therapeutics made up 15.2% of Atlas Venture Life Science Advisors's portfolio in Q1 2026, its #3 holding.
  • Atlas Venture Life Science Advisors first reported a position in Sionna Therapeutics in Q1 2025 and has held it in 5 quarters since.
  • Atlas Venture Life Science Advisors's Sionna Therapeutics position peaked at $123M in Q4 2025.
  • 122 funds tracked by Wall St. Rank held Sionna Therapeutics as of Q1 2026.

Based on Atlas Venture Life Science Advisors's 13F filing for Q1 2026, filed 14 May 2026.