Companies / Sionna Therapeutics, Inc.
Sionna Therapeutics, Inc.
Nasdaq: SIONCIK 2036042WALTHAM, MA
Financials
Ownership
45.2M shares outstanding · as of Jul 31, 2026
Ownership
| Insiders | 11.82% | 5,343,543 |
| 10%+ / strategic | 14.37% | 6,494,962 |
| Institutions | 82.85% | 37,457,153 |
| Public float | 0.00% | 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
View all →| Insider | % of shares | Shares |
|---|---|---|
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
View all →| Holder | Value | % of shares |
|---|---|---|
| $397.09M | 21.91% | |
| $277.49M | 14.92% | |
| $141.55M | 7.81% | |
| $128.09M | 7.07% | |
| $123.24M | 6.63% | |
| $101.95M | 5.48% | |
| $64.88M | 3.26% | |
| $50.68M | 2.72% | |
| $48.75M | 2.62% | |
| $45.88M | 2.47% |
Activity
Jun 30, 2026View all →
InsidersInstitutions
Who's accumulating and trimming this stock (13F).| Date | Actor | Action | Security | Value | Shares Δ | Position after | Impact |
|---|---|---|---|---|---|---|---|
| Q1 2026 as of | Perceptive Advisors LLC 13F manager | Trim | — | $-20.87M | -521K -44.16% | 658,439 1.46% of shares | medium |
| Q2 2026 as of | State Street Corporation 13F manager | Add | — | $14.43M | +328K +47.32% | 1,021,534 2.26% of shares | medium |
| Q2 2026 as of | BlackRock, Inc. 13F manager | Add | — | $8.06M | +183K +14.18% | 1,474,769 3.26% of shares | medium |
| Q1 2026 as of | Adage Capital Partners Gp, L.L.C. 13F manager | New | — | $6.01M | +150K | 150,000 0.33% of shares | medium |
| Q1 2026 as of | Millennium Management LLC 13F manager | Add | — | $2.41M | +60K +74.61% | 140,641 0.31% of shares | low |
| Q2 2026 as of | Deutsche Bank AG 13F manager | Add | — | $1.91M | +43K +431.99% | 53,353 0.12% of shares | low |
| Q1 2026 as of | BNP Paribas Financial Markets 13F manager | Add | — | $1.54M | +38K +1691.96% | 40,570 0.09% of shares | low |
| Q4 2025 as of | Bank of America Corp /De 13F manager | Add | — | $1.52M | +37K +566.06% | 43,567 0.10% of shares | low |
5%+ ownership events
Schedule 13D / 13G
| Filer | Stance | % of class |
|---|---|---|
| Viking Global Investors LP | Passive13G/A | — |
Securities
via CUSIP / OpenFIGI
| Symbol | Type | CUSIP |
|---|---|---|
| SION | — | 829401108 |