As of November 10, 2026, Sionna Therapeutics, Inc. is a publicly traded company (Nasdaq: SION). The largest holder reporting an active stake on Schedule 13D is RA Capital, at 14.3%. No bankruptcy or receivership appears in its SEC Form 8-K filings. Passive holders reporting on Schedule 13G include Viking Global (7.1%), Goldman Sachs (5.8%) (Schedule 13D/A, September 21, 2026).
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Is Sionna Therapeutics, Inc. a real, registered company?
- Sionna Therapeutics, Inc. files with the SEC under CIK 2036042 (its SEC filings).
- Its shares are listed under the ticker SION on Nasdaq (SEC company record).
- Incorporated in Delaware; business address in Waltham, Massachusetts, as its SEC filings state.
- Court and bankruptcy records: see Before you sign or pay below.
Before you sign or pay
- Court and bankruptcy: No federal court case or bankruptcy filing found under SIONNA THERAPEUTICS, INC. in our court records and SEC 8-K records (as of 2026-11-10).
- Layoffs: 1 exit or restructuring plan reported on Form 8-K, Item 2.05 (latest filed 2026-09-14).
- Ownership: 5%+ holders are reported on Schedule 13D or 13G; the latest names Goldman Sachs (filed 2026-11-09).
Who are Sionna Therapeutics, Inc.'s owners and officers?
Sionna Therapeutics, Inc.: incorporated in Delaware; business address in Waltham, Massachusetts; industry Pharmaceutical Preparations (Schedule 13G, 2026-11-09).
| Report | Holder | Share |
|---|---|---|
| Schedule 13G, 2026-11-09 | The Goldman Sachs Group, Inc. | 5.8% |
| Schedule 13D/A, 2026-09-21 | Ra Capital Management, L.P. | 14.3% |
| Schedule 13G/A, 2026-05-15 | Viking Global Investors LP | 7.1% |
| Schedule 13G/A, 2026-05-12 | Qatar Investment Authority | 4.5% |
| Schedule 13D/A, 2026-04-20 | Orbimed Advisors LLC | 6.6% |
| Schedule 13D/A, 2025-11-07 | Ra Capital Management, L.P. | 22.6% |
| Schedule 13G/A, 2025-10-31 | Jpmorgan Chase & Co. | 4.4% |
| Schedule 13D/A, 2025-10-20 | Atlas Venture Fund Xi, L.P. | 5.4% |
| Schedule 13G, 2025-07-30 | Jpmorgan Chase & Co. | 5% |
Questions about who owns Sionna Therapeutics, Inc.
Who owns Sionna Therapeutics, Inc.?
On this page, 5 holders' latest ownership filings report 5% or more of Sionna Therapeutics, Inc.: Ra Capital Management, L.P. (14.3%, Schedule 13D/A, filed 2026-09-21), Viking Global Investors LP (7.1%, Schedule 13G/A, filed 2026-05-15), Orbimed Advisors LLC (6.6%, Schedule 13D/A, filed 2026-04-20), The Goldman Sachs Group, Inc. (5.8%, Schedule 13G, filed 2026-11-09) and Atlas Venture Fund Xi, L.P. (5.4%, Schedule 13D/A, filed 2025-10-20).
Who are the largest shareholders of Sionna Therapeutics, Inc.?
By the share each holder's latest filing reports, the largest holders of Sionna Therapeutics, Inc. on this page are Ra Capital Management, L.P. (14.3%), Viking Global Investors LP (7.1%) and Orbimed Advisors LLC (6.6%).
When did Ra Capital Management, L.P. buy into Sionna Therapeutics, Inc.?
The filings give report dates, not purchase dates. The earliest filing from Ra Capital Management, L.P. on this page is the Schedule 13D/A, filed 2025-11-07, reporting 22.6%; its latest, Schedule 13D/A filed 2026-09-21, reports 14.3%. That earliest filing is itself an amendment, which updates an earlier report.
Is this an audit or a full list?
Neither. The ownership list on this page covers only Schedule 13D and 13G filings, which holders make once they own 5% or more of a class of shares (an amendment can report a stake that has since fallen below 5%); 9 such filings are shown here. It is not an audit and not a full cap table: holders who never reached 5% are not listed, and a stake can change after its latest filing.
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Which insiders own Sionna Therapeutics, Inc. shares?
Directors, officers and holders of 10% or more report their shares on Forms 3, 4 and 5. Each line is the latest such report, largest holding first.
- TPG GP A, LLC, a 10% owner: 6,494,962 shares (14.4% of shares outstanding), held indirectly (the form names the holder only in its footnotes), on a joint filing (Form 4, 2026-01-26).
- , a 10% owner: 6,494,962 shares (14.4% of shares outstanding), held indirectly (the form names the holder only in its footnotes), on a joint filing (Form 4, 2026-01-26).
- , a 10% owner: 6,494,962 shares (14.4% of shares outstanding), held indirectly (the form names the holder only in its footnotes), on a joint filing (Form 4, 2026-01-26).
- Atlas Venture Fund XI, L.P., a 10% owner: 4,441,747 shares (9.8% of shares outstanding), 2,886,293 held directly and 1,555,454 indirectly, on a joint filing (Form 4, 2025-02-10).
- Atlas Venture Associates XI, LLC, a 10% owner: 4,441,747 shares (9.8% of shares outstanding), 2,886,293 held directly and 1,555,454 indirectly, on a joint filing (Form 4, 2025-02-10).
Shares outstanding: 45,212,399 as of 2026-07-31, from the company's latest SEC cover page.
How much has Sionna Therapeutics, Inc. raised?
Latest IPO step: Sionna Therapeutics, Inc. filed its final IPO prospectus (424B4, 2025-02-07).
IPO filings: 424B4, 2025-02-07, S-1/A, 2025-02-03, S-1, 2025-01-17.
Red flags found
1 exit or restructuring plan on Form 8-K (latest Form 8-K, 2026-09-14).
Keep reading
More on Sionna Therapeutics, Inc. and the records around it.
Sionna Therapeutics, Inc. elsewhere on the record
- 5%+ stake filings Nov 2026
- Layoff notices Sep 2026
Companies that share a holder
- Atlas Venture Fund XI, L.P. also filed stake reports on 3 other companies: DYNE THERAPEUTICS, INC. (Aug 2026), Korro Bio, Inc. (Aug 2026), Day One Biopharmaceuticals, Inc. (May 2026)
- Qatar Investment Authority also filed stake reports on 11 other companies: Aspen Neuroscience, Inc. (Nov 2026), Global Business Travel Group, Inc. (Sep 2026), Nanobiotix SA (Jul 2026)
- VIKING GLOBAL INVESTORS LP also filed stake reports on 27 other companies: City Therapeutics, Inc. (Oct 2026), MID AMERICA APARTMENT COMMUNITIES INC. (Oct 2026), REGAL REXNORD CORP (Sep 2026)
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