Sionna Therapeutics, Inc.
Ownership
Ownership Structure
Who owns Sionna Therapeutics, Inc. (SION)? This page shows the largest institutions and funds, the ownership structure and the latest insider transactions. 45.3% of the shares are freely tradable; institutional investors hold 100.3%.
Largest Shareholders
Institutions
| Name | Stake (%) | Shares | Change (%) | Date |
|---|---|---|---|---|
| RA Capital Management, LLC | 21.91 | 9,905,045 | +0.0 | 06/30/2026 |
| TPG GP A, LLC | 14.37 | 6,494,962 | +0.0 | 06/30/2026 |
| Viking Global Investors LP | 7.07 | 3,195,181 | +0.0 | 06/30/2026 |
| Atlas Venture Life Science Advisors, LLC | 6.63 | 2,995,602 | +0.0 | 06/30/2026 |
| Orbimed Advisors LLC | 5.65 | 2,555,877 | -27.6 | 06/30/2026 |
| Enavate Sciences GP, LLC | 5.48 | 2,478,030 | +0.0 | 06/30/2026 |
| Adage Capital Partners Gp LLC | 3.54 | 1,600,000 | +966.7 | 06/30/2026 |
| JPMorgan Chase & Co | 3.30 | 1,490,508 | +1.7 | 06/30/2026 |
| BlackRock Inc | 3.26 | 1,474,769 | +13.8 | 06/30/2026 |
| Jennison Associates LLC | 2.59 | 1,172,133 | -19.2 | 06/30/2026 |
Largest reported positions according to regulatory filings; stake as a percentage of shares outstanding, change versus the previous filing. Source: fundamentals data.
Insider holdings
| Person | Role | Shares | Value | As of | Type |
|---|---|---|---|---|---|
| Ra Capital Management, L.p. | Director | 3,448,812 | 13,450,367 $ | Sep 17, 2026 | indirect |
| Thompson Peter A. | Director | 2,469,959 | 9,632,840 $ | Jul 7, 2026 | indirect |
| Orbimed Advisors Llc | Director | 2,469,959 | 9,632,840 $ | Jul 7, 2026 | indirect |
| Cloonan Michael | President & CEO | 765,393 | 2,985,033 $ | Sep 17, 2026 | direct |
| Ridloff Elena | CFO and CBO | 133,069 | 518,969 $ | Sep 17, 2026 | direct |
| McKee Charlotte | CMO and Head of R&D | 128,415 | 500,819 $ | Sep 17, 2026 | direct |
| Fitzpatrick Jennifer | CLO and Head of Program Mgmt. | 56,265 | 219,434 $ | Sep 17, 2026 | direct |
Holdings as of each person's most recent SEC Form 4 filing — excluding options and RSUs, which are not shares yet. Holdings may have changed between two filings.
Insiders
Insider Transactions
| Date | Person | Role | Type | Shares | Price | Value |
|---|---|---|---|---|---|---|
| Sep 17, 2026 | Ra Capital Management, L.p. | Director | Sell | 33,800 | 7.46 | 252,148 |
| Sep 17, 2026 | Ra Capital Management, L.p. | Director | Sell | 3,415,011 | 6.32 | 21,582,870 |
| Sep 17, 2026 | Fitzpatrick Jennifer | CLO and Head of Program Mgmt. | Other | 28,132 | 0.00 | – |
| Sep 17, 2026 | Fitzpatrick Jennifer | CLO and Head of Program Mgmt. | Other | 28,133 | 0.00 | – |
| Sep 17, 2026 | McKee Charlotte | CMO and Head of R&D | Other | 50,000 | 0.00 | – |
| Sep 17, 2026 | Ridloff Elena | CFO and CBO | Other | 47,268 | 0.00 | – |
| Sep 17, 2026 | Ridloff Elena | CFO and CBO | Other | 47,269 | 0.00 | – |
| Sep 17, 2026 | Cloonan Michael | President & CEO | Other | 109,025 | 0.00 | – |
| Jul 7, 2026 | Thompson Peter A. | Director | Sell | 85,918 | 44.86 | 3,854,281 |
| Jul 7, 2026 | Orbimed Advisors Llc | Director | Sell | 85,918 | 44.86 | 3,854,281 |
| Apr 18, 2026 | Orbimed Advisors Llc | Director | Sell | 2,948 | 44.52 | 131,245 |
| Apr 18, 2026 | Peter A Thompson | Director | Sell | 2,948 | 44.52 | 131,245 |
| Apr 17, 2026 | Orbimed Advisors Llc | Director | Sell | 52,397 | 44.68 | 2,341,098 |
| Apr 17, 2026 | Peter A Thompson | Director | Sell | 52,397 | 44.68 | 2,341,098 |
Reportable transactions by officers and major shareholders from SEC Form 4 filings. "Other" includes things like stock grants and option exercises without a buy/sell character. View all insider transactions →
Data as of: October 30, 2026 · Source: fundamental data & SEC filings (annual and quarterly reports, 10-K/10-Q)
Note: pure fact-based analysis, not investment advice and not a solicitation to buy or sell. All figures without guarantee.