JB
SION

Julian Baker’s Sionna Therapeutics SION Stock Holding History

Julian Baker’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 		$17.6M Hold
400,000
– – 0.09% 61
2026
Q1 		$16M Hold
400,000
– – 0.09% 61
2025
Q4 		$16.5M Hold
400,000
– – 0.1% 60
2025
Q3 		$11.8M Hold
400,000
– – 0.09% 62
2025
Q2 		$6.94M Hold
400,000
– – 0.07% 60
2025
Q1 		$4.18M Buy
+400,000
New +$6.54M 0.05% 62

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
AVLSA
Atlas Venture Life Science Advisors Cambridge, Massachusetts $881M AUM 160.77% 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

Julian Baker's SION Position: Q2 2026 in Review

Julian Baker held its Sionna Therapeutics (SION) position steady in Q2 2026 at 400,000 shares worth $17.6M. The position accounts for 0.09% of the portfolio, ranked #61.

Julian Baker first reported a position in SION in Q1 2025 and has held it in 6 quarters since. 146 funds tracked by Wall St. Rank hold SION as of Q2 2026.

  • Julian Baker held 400,000 shares of Sionna Therapeutics worth $17.6M as of Q2 2026.
  • Julian Baker left its Sionna Therapeutics share count unchanged in Q2 2026.
  • Sionna Therapeutics made up 0.09% of Julian Baker's portfolio in Q2 2026, its #61 holding.
  • Julian Baker first reported a position in Sionna Therapeutics in Q1 2025 and has held it in 6 quarters since.
  • 146 funds tracked by Wall St. Rank held Sionna Therapeutics as of Q2 2026.

Based on Baker Bros. Advisors's 13F filing for Q2 2026, filed 14 Aug 2026.