Companies / Sionna Therapeutics, Inc.

Sionna Therapeutics, Inc.

Nasdaq: SIONCIK 2036042WALTHAM, MA

Financials

Revenue—
Net income$-75.27M
Total debt—
Cash$63.32M
Diluted EPS$-1.88
Shares outstanding45.2M

Ownership

45.2M shares outstanding · as of Jul 31, 2026
11.8%Insiders
Ownership
Insiders11.82%5,343,543
10%+ / strategic14.37%6,494,962
Institutions82.85%37,457,153
Public float0.00%0

Reported holdings exceed shares outstanding — public float shown as 0; some positions may overlap or lag.

% of common shares outstanding (exact, from the latest cover-page filing). Institutions are quarterly 13F snapshots; insiders reflect current officers & directors.

Insiders 17

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Insider% of sharesShares
Tpg Gp a, LLC10% owner
14.37%6,494,962
Orbimed Advisors LLCFormerDirector
11.82%5,343,543
Thompson Peter A.Director
11.82%5,343,543
Fitzpatrick JenniferFormerChief Legal Officer
0.00%0
Beer Caroline StarkChief Business Officer
——
Cloonan MichaelCEOPresident & CEO · Director
——
Coulter James G10% owner
——
Kolchinsky PeterFormerDirector · 10% owner
——
McKee CharlotteFormerChief Medical Officer
——
OrbiMed Capital GP VIII LLCFormerDirector
——

Institutional holders 107

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HolderValue% of shares
RA Capital Management, L.P.$397.09M21.91%
Tpg Gp a, LLC$277.49M14.92%
Orbimed Advisors LLC$141.55M7.81%
Viking Global Investors LP$128.09M7.07%
Atlas Venture Life Science Advisors, LLC$123.24M6.63%
Enavate Sciences GP, LLC$101.95M5.48%
BlackRock, Inc.$64.88M3.26%
JPMORGAN CHASE & CO$50.68M2.72%
Vanguard Group Inc$48.75M2.62%
Jennison Associates LLC$45.88M2.47%

Activity

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InsidersInstitutions
What insiders are doing in this stock (Form 4).
DateActorActionSecurityValueShares ΔPosition afterImpact
Apr 15, 2026Thompson Peter A.
Director
SellCommon Stock$10.53M-236K
-6.77%
3,247,025
7.18% of shares
medium
Apr 15, 2026Orbimed Advisors LLC
Director
SellCommon Stock$10.53M-236K
-6.77%
3,247,025
7.18% of shares
medium
Apr 16, 2026Thompson Peter A.
Director
SellCommon Stock$10.29M-227K
-6.99%
3,020,119
6.68% of shares
medium
Apr 16, 2026Orbimed Advisors LLC
Director
SellCommon Stock$10.29M-227K
-6.99%
3,020,119
6.68% of shares
medium
Jan 22, 2026Tpg Gp a, LLC
10% owner
SellCommon Stock$10.00M-250K
-3.71%
6,494,962
14.37% of shares
medium
May 11, 2026Thompson Peter A.
Director
SellCommon Stock$8.53M-185K
-6.46%
2,671,822
5.91% of shares
medium
May 11, 2026Orbimed Advisors LLC
Director
SellCommon Stock$8.53M-185K
-6.46%
2,671,822
5.91% of shares
medium
May 8, 2026Thompson Peter A.
Director
SellCommon Stock$2.66M-60K
-2.05%
2,856,461
6.32% of shares
medium

5%+ ownership events

Schedule 13D / 13G
FilerStance% of classSharesDate
Viking Global Investors LPPassive13G/A———

Securities

via CUSIP / OpenFIGI
SymbolTypeMarketCUSIPFIGI
SION——829401108—