Sionna Therapeutics, Inc. has 8 Schedule 13D or 13G filings on record since 2025-07-30. 4 holders' latest filing reports 5% or more of common stock, $0.001 par value per share. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| RA Capital Management, L.P. | 14.3% | 6,476,193 | SCHEDULE 13D/A, 2026-09-21 | 2026-09-17 |
| Viking Global Investors LP | 7.1% | 3,195,181 | SCHEDULE 13G/A, 2026-05-15 | 2026-03-31 |
| Orbimed Advisors LLC | 6.6% | 2,967,722 | SCHEDULE 13D/A, 2026-04-20 | 2026-04-15 |
| Atlas Venture Fund XI, L.P. | 5.4% | 2,382,495 | SCHEDULE 13D/A, 2025-10-20 | 2025-10-16 |
| Qatar Investment Authority | 4.5% | 2,020,258 | SCHEDULE 13G/A, 2026-05-12 | 2026-03-31 |
| Jpmorgan Chase & Co. | 4.4% | 1,980,626 | SCHEDULE 13G/A, 2025-10-31 | 2025-09-30 |
Purpose of Transaction (Item 4)
Orbimed Advisors LLC
The Reporting Persons from time to time intend to review their investment in the Issuer on the basis of various factors, including the Issuer's business, financial condition, results of operations and prospects, general economic and industry conditions, the securities markets in general and those for the Issuer's Shares in particular, as well as other developments and other investment opportunities. Based upon such review, the Reporting Persons will take such actions in the future as the Reporting Persons may deem appropriate in light of the circumstances existing from time to time. If the Reporting Persons believe that further investment in the Issuer is attractive, whether because of the market price of Shares or otherwise, they may acquire Shares or other securities of the Issuer either in the open market or in privately negotiated transactions. Similarly, depending on market and other factors, the Reporting Persons may determine to dispose of some or all of the Shares currently owned by the Reporting Persons or otherwise acquired by the Reporting Persons either in the open market or in privately negotiated transactions. Except as set forth in this Schedule 13D, the Reporting Persons have not formulated any plans or proposals which relate to or would result in: (a) the acquisition by any person of additional securities of the Issuer or the disposition of securities of the Issuer, (b) an extraordinary corporate transaction, such as a merger, reorganization or liquidation, …The first part of Item 4 of the SCHEDULE 13D/A filed 2026-04-20; the filing has the rest
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-07-30 | Jpmorgan Chase & Co. | 5% | SCHEDULE 13G |
| 2025-10-20 | Atlas Venture Fund XI, L.P. | 5.4% | SCHEDULE 13D/A |
| 2025-10-31 | Jpmorgan Chase & Co. | 4.4% | SCHEDULE 13G/A |
| 2025-11-07 | RA Capital Management, L.P. | 22.6% | SCHEDULE 13D/A |
| 2026-04-20 | Orbimed Advisors LLC | 6.6% | SCHEDULE 13D/A |
| 2026-05-12 | Qatar Investment Authority | 4.5% | SCHEDULE 13G/A |
| 2026-05-15 | Viking Global Investors LP | 7.1% | SCHEDULE 13G/A |
| 2026-09-21 | RA Capital Management, L.P. | 14.3% | SCHEDULE 13D/A |
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Where this comes from
Anyone who comes to own more than 5% of a class of a listed company's voting shares has to tell the SEC. A holder who may seek to change or influence the company files Schedule 13D, and has to say in Item 4, "Purpose of Transaction", what it intends to do. A holder with no such intent, such as many index and passive funds, may file the shorter Schedule 13G. Both are amended when the stake changes, including when it falls below 5%.
Every row here is one of those filings, linked to the filing itself. Percentages and share counts are exactly as the holder filed them, for the holder the filing names; an amendment showing a lower figure is shown as filed. Item 4 text is quoted word for word. Where a 13D's Item 4 contains a sentence stating a definite intent to influence the company, that sentence is marked and quoted; the page does not describe the holder or its motives beyond the words it filed. Nothing here is investment advice.