SIONNA THERAPEUTICS INC SION
COM · Common Stock · CUSIP 829401108
- SectorHealth care
- IndustryPharmaceutical Preparations
- HeadquartersWaltham, MA
- FilingsSEC EDGAR
* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once ($93.9k this quarter). Holder counts are more reliable. Shares outstanding: 45.2m as of 2026-07-31, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $43.87. Options: 4 managers hold calls ($1.5m notional), 5 hold puts ($8.1m).
Trends to Q2 2026
Institutional holders
Managers reporting a position, each quarter
Numbers
| Quarter | Holders |
|---|---|
| Q1 2025 | 48 |
| Q2 2025 | 66 |
| Q3 2025 | 78 |
| Q4 2025 | 101 |
| Q1 2026 | 122 |
| Q2 2026 | 147 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q2 2025 | 44 | 18 |
| Q3 2025 | 40 | 24 |
| Q4 2025 | 66 | 27 |
| Q1 2026 | 69 | 39 |
| Q2 2026 | 91 | 48 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q3 2025 | $0 | $0 | — |
| Q4 2025 | $0 | $0 | — |
| Q1 2026 | $0 | $0 | — |
| Q2 2026 | $1.5m | $8.1m | 5.45 |
Biggest buyers
| ADAGE CAPITAL PARTNERS GP, L.L.C. | Added | +1.4m |
| Casdin Capital, LLC | New | +400.0k |
| Siren, L.L.C. | Added | +310.5k |
| Driehaus Capital Management LLC | Added | +308.8k |
| STATE STREET CORP | Added | +265.3k |
| PERCEPTIVE ADVISORS LLC | Added | +246.6k |
| FMR LLC | Added | +196.9k |
| Artisan Partners Limited Partnership | New | +189.5k |
| Longaeva Partners L.P. | Added | +183.7k |
| BlackRock, Inc. | Added | +178.9k |
Biggest sellers
| ORBIMED ADVISORS LLC | Reduced | -974.8k |
| DEERFIELD MANAGEMENT COMPANY, L.P. | Reduced | -289.7k |
| Aberdeen Group plc | Reduced | -280.0k |
| JENNISON ASSOCIATES LLC | Reduced | -279.1k |
| PRICE T ROWE ASSOCIATES INC /MD/ | Reduced | -278.4k |
| EVENTIDE ASSET MANAGEMENT, LLC | Reduced | -170.5k |
| Sio Capital Management, LLC | Reduced | -166.5k |
| Soleus Capital Management, L.P. | Reduced | -115.8k |
| Point72 Asset Management, L.P. | Reduced | -87.2k |
| SUPERSTRING CAPITAL MANAGEMENT LP | Reduced | -77.9k |
Biggest calls
| MILLENNIUM MANAGEMENT LLC | New | $879.8k20.0k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | New | $356.3k8.1k shares |
| Verition Fund Management LLC | New | $219.9k5.0k shares |
| SIMPLEX TRADING, LLC | New | $35.2k800 shares |
Biggest puts
| Ikarian Capital, LLC | New | $4.7m107.5k shares |
| BOOTHBAY FUND MANAGEMENT, LLC | New | $1.4m32.5k shares |
| MILLENNIUM MANAGEMENT LLC | New | $1.3m28.6k shares |
| CITADEL ADVISORS LLC | New | $369.5k8.4k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | New | $338.7k7.7k shares |
Options at notional value: the value of the shares the contracts control, as filers report them, not what the options cost. Not included in the holders, shares or buying above.
Major shareholders (over 5%)
Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.
| Holder | Stake |
|---|---|
TPG GP A, LLC
13D · may seek influence
new · filed 2025-02-18
Stated purposeThe information set forth in or incorporated by reference in Items 2, 3, 5 and 6 of this Schedule 13D is incorporated by reference in its entirety into this Item 4. Initial Public Offering On February 6, 2025, the Issuer entered into an underwriting agreement (the "Underwriting Agreement") with Goldman Sachs & Co. LLC, TD Securities (USA) LLC, Stifel, Nicolaus & Company, Incorporated and Guggenheim Securities, LLC (the "Underwriters") providing for the offer and sale by the Issuer (the "Offering"), and purchase by the Underwriters, of 10,588,233 shares of Common Stock at a price to the public of $18.00 per share. On February 10, 2025, the Offering closed (the "Closing"). The Rise Fund Sling, L.P. purchased 1,125,000 shares of Common Stock in the Offering at a price of $18.00 per share … Full filing |
15.2% |
| RA CAPITAL MANAGEMENT, L.P. 13D · may seek influence -8.3 pts · filed 2026-09-21 | 14.3% |
| VIKING GLOBAL INVESTORS LP 13G · passive investor +0.4 pts · filed 2026-05-15 | 7.1% |
ORBIMED ADVISORS LLC
13D · may seek influence
-1.8 pts · filed 2026-04-20
Stated purposeThe 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… Full filing |
6.6% |
Enavate Sciences GP, LLC
13D · may seek influence
new · filed 2025-02-18
Stated purposeThe Reporting Persons purchased the aforementioned securities for investment purposes with the aim of increasing the value of their investments and the Issuer. Subject to applicable legal requirements, one or more of the Reporting Persons may purchase additional securities of the Issuer from time to time in open market or private transactions, depending on its evaluation of the Issuer's business, prospects and financial condition, the market for the Issuer's securities, other developments concerning the Issuer, the reaction of the Issuer to the Reporting Persons' ownership of the Issuer's securities, other opportunities available to the Reporting Persons, and general economic, money market and stock market conditions. In addition, depending upon the factors referred to above, the Reportin… Full filing |
5.6% |
| Atlas Venture Fund XI, L.P. 13D · may seek influence -1.1 pts · filed 2025-10-20 | 5.4% |
Fell to 5% or below in the last year: Qatar Investment Authority (4.5%, 2026-05-12)
Insider purchases and sales since 1 Apr 2026
Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.
Officers and directors buying vs selling
Number of people, by quarter (10% owners not included)
Numbers
| Quarter | Buying | Bought | Selling | Sold | Sold under a plan |
|---|---|---|---|---|---|
| Q4 2024 | 0 | — | 0 | — | — |
| Q1 2025 | 4 | $31.2m | 0 | — | — |
| Q2 2025 | 0 | — | 0 | — | — |
| Q3 2025 | 0 | — | 4 | $6.5m | $6.5m |
| Q4 2025 | 0 | — | 6 | $52.4m | $30.9m |
| Q1 2026 | 0 | — | 3 | $1.7m | $1.7m |
| Q2 2026 | 0 | — | 2 | $44.1m | $44.1m |
| Q3 2026 | 0 | — | 4 | $4.3m | $4.3m |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2026-09-17 | RA CAPITAL MANAGEMENT, L.P. +5 Director · See footnotes | Sold | —3.4m shares |
| 2026-07-07 | ORBIMED ADVISORS LLC +1 Director · See footnotes | Sold plan | $3.9m85.9k shares |
| 2026-07-07 | Thompson Peter A. Director · See footnotes | Sold plan | $3.9m85.9k shares |
| 2026-07-06 | Fitzpatrick Jennifer Chief Legal Officer | Sold plan | $446.9k10.2k shares |
| 2026-06-30 | ORBIMED ADVISORS LLC +1 Director · See footnotes | Sold plan | $5.3m115.8k shares |
| 2026-06-30 | Thompson Peter A. Director · See footnotes | Sold plan | $5.3m115.8k shares |
| 2026-05-27 | ORBIMED ADVISORS LLC +1 Director · See footnotes | Sold plan | $4.5k101 shares |
| 2026-05-27 | Thompson Peter A. Director · See footnotes | Sold plan | $4.5k101 shares |
| 2026-05-11 | ORBIMED ADVISORS LLC +1 Director · See footnotes( | Sold plan | $8.5m184.6k shares |
| 2026-05-11 | Thompson Peter A. Director · See footnotes( | Sold plan | $8.5m184.6k shares |
| 2026-05-08 | ORBIMED ADVISORS LLC +1 Director · See footnotes( | Sold plan | $2.7m59.8k shares |
| 2026-05-08 | Thompson Peter A. Director · See footnotes( | Sold plan | $2.7m59.8k shares |
| 2026-05-07 | ORBIMED ADVISORS LLC +1 Director · See footnotes( | Sold plan | $2.2m48.5k shares |
| 2026-05-07 | Thompson Peter A. Director · See footnotes( | Sold plan | $2.2m48.5k shares |
| 2026-04-18 | ORBIMED ADVISORS LLC +1 Director · See footnotes | Sold plan | $131.2k2.9k shares |
| 2026-04-18 | Thompson Peter A. Director · See footnotes | Sold plan | $131.2k2.9k shares |
| 2026-04-17 | ORBIMED ADVISORS LLC +1 Director · See footnotes | Sold plan | $2.3m52.4k shares |
| 2026-04-17 | Thompson Peter A. Director · See footnotes | Sold plan | $2.3m52.4k shares |
| 2026-04-16 | ORBIMED ADVISORS LLC +1 Director · See footnotes | Sold plan | $10.3m226.9k shares |
| 2026-04-16 | Thompson Peter A. Director · See footnotes | Sold plan | $10.3m226.9k shares |
| 2026-04-15 | ORBIMED ADVISORS LLC +1 Director · See footnotes | Sold plan | $10.5m235.9k shares |
| 2026-04-15 | Thompson Peter A. Director · See footnotes | Sold plan | $10.5m235.9k shares |
| 2026-04-14 | ORBIMED ADVISORS LLC +1 Director · See footnotes | Sold plan | $2.1m47.8k shares |
| 2026-04-14 | Thompson Peter A. Director · See footnotes | Sold plan | $2.1m47.8k shares |
Their holding: how much the trade added to or took from the insider's holding (direct, or the trust or fund named). The same trade is sometimes reported by more than one insider, such as a fund and the director who represents it; totals count it once. A value is left blank where the reported price is far from the market price (usually a typo).
Holders, Q2 2026
| Manager | Shares | Change |
|---|---|---|
| RA CAPITAL MANAGEMENT, L.P. 3.79% of their portfolio | 9.9m $435.7m | Unchanged |
| TPG GP A, LLC 5.71% of their portfolio | 6.5m $285.7m | Unchanged |
| VIKING GLOBAL INVESTORS LP 0.40% of their portfolio | 3.2m $140.6m | Unchanged |
| Atlas Venture Life Science Advisors, LLC 14.95% of their portfolio | 3.0m $131.8m | Unchanged |
| ORBIMED ADVISORS LLC 2.13% of their portfolio | 2.6m $112.4m | Reduced -974.8k |
| ENAVATE SCIENCES GP, LLC 31.56% of their portfolio | 2.5m $109.0m | Unchanged |
| ADAGE CAPITAL PARTNERS GP, L.L.C. 0.10% of their portfolio | 1.6m $70.4m | Added +1.4m |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 1.5m $64.1m | Added +25.5k |
| BlackRock, Inc. 0.00% of their portfolio | 1.5m $64.9m | Added +178.9k |
| JENNISON ASSOCIATES LLC 0.03% of their portfolio | 1.2m $51.6m | Reduced -279.1k |
| CITADEL ADVISORS LLC 0.03% of their portfolio | 1.1m $50.5m | Reduced -19.3k |
| VANGUARD CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 1.1m $49.8m | Added +102.5k |
| STATE STREET CORP 0.00% of their portfolio | 1.0m $44.9m | Added +265.3k |
| PERCEPTIVE ADVISORS LLC 0.62% of their portfolio | 905.0k $39.8m | Added +246.6k |
| DEERFIELD MANAGEMENT COMPANY, L.P. 0.31% of their portfolio | 680.9k $30.0m | Reduced -289.7k |
| Siren, L.L.C. 0.55% of their portfolio | 610.5k $26.9m | Added +310.5k |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio | 478.0k $21.0m | Reduced -278.4k |
| EVENTIDE ASSET MANAGEMENT, LLC 0.28% of their portfolio | 475.0k $20.9m | Reduced -170.5k |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 457.1k $20.1m | Added +67.3k |
| BAKER BROS. ADVISORS LP 0.09% of their portfolio | 400.0k $17.6m | Unchanged |
| Casdin Capital, LLC 0.88% of their portfolio | 400.0k $17.6m | New |
| Kalehua Capital Management LLC 5.53% of their portfolio | 394.1k $17.3m | Unchanged |
| GOLDMAN SACHS GROUP INC 0.00% of their portfolio | 388.8k $17.1m | Added +125.6k |
| Driehaus Capital Management LLC 0.10% of their portfolio | 385.4k $17.0m | Added +308.8k |
| FRANKLIN RESOURCES INC 0.00% of their portfolio | 290.1k $12.8m | Added +114.6k |
| Aberdeen Group plc 0.02% of their portfolio | 284.1k $12.5m | Reduced -280.0k |
| FMR LLC 0.00% of their portfolio | 278.3k $12.2m | Added +196.9k |
| MILLENNIUM MANAGEMENT LLC 0.01% of their portfolio | 276.7k $12.2m | Added +136.1k |
| Candriam S.C.A. 0.05% of their portfolio | 233.2k $10.2m | Reduced -3.6k |
| VANGUARD PORTFOLIO MANAGEMENT LLC 0.00% of their portfolio | 222.9k $9.8m | Added +80.9k |
| Longaeva Partners L.P. 0.25% of their portfolio | 196.4k $8.6m | Added +183.7k |
| Artisan Partners Limited Partnership 0.01% of their portfolio | 189.5k $8.3m | New |
| Ensign Peak Advisors, Inc 0.01% of their portfolio | 184.5k $8.1m | Reduced -71.1k |
| Soleus Capital Management, L.P. 0.27% of their portfolio | 177.7k $7.8m | Reduced -115.8k |
| NORTHERN TRUST CORP 0.00% of their portfolio | 154.5k $6.8m | Added +37.7k |
| MORGAN STANLEY 0.00% of their portfolio | 151.0k $6.6m | Added +18.0k |
| Sofinnova Investments, Inc. 0.34% of their portfolio | 144.4k $6.4m | New |
| Qube Research & Technologies Ltd 0.01% of their portfolio | 140.3k $6.2m | Added +98.1k |
| Alyeska Investment Group, L.P. 0.02% of their portfolio | 136.2k $6.0m | Unchanged |
| GordonMD Global Investments LP 2.89% of their portfolio | 136.0k $6.0m | Unchanged |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 129.8k $5.7m | Added +9.5k |
| Sio Capital Management, LLC 0.96% of their portfolio | 127.8k $5.6m | Reduced -166.5k |
| Ishara Investments LP 0.99% of their portfolio | 123.0k $1.4m | Added +73.8k |
| VANGUARD FIDUCIARY TRUST CO 0.00% of their portfolio | 121.4k $5.3m | Added +9.3k |
| Artia Global Partners LP 1.00% of their portfolio | 119.7k $5.3m | Unchanged |
| UBS Group AG 0.00% of their portfolio | 116.2k $5.1m | Reduced -31.4k |
| First Turn Management, LLC 0.52% of their portfolio | 110.5k $4.9m | New |
| CITIGROUP INC 0.00% of their portfolio | 110.2k $4.8m | Added +92.1k |
| D. E. Shaw & Co., Inc. 0.00% of their portfolio | 101.6k $4.5m | New |
| Rock Springs Capital Management LP 0.21% of their portfolio | 99.4k $4.4m | Unchanged |
| Walleye Capital LLC 0.02% of their portfolio | 97.3k $4.3m | Added +82.2k |
| Rhenman & Partners Asset Management AB 0.40% of their portfolio | 97.1k $4.3m | Added +9.6k |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 88.9k $3.9m | Added +38.0k |
| AMERIPRISE FINANCIAL INC 0.00% of their portfolio | 82.2k $3.6m | Added +258 |
| Integral Health Asset Management, LLC 0.14% of their portfolio | 75.0k $3.3m | Added +25.0k |
| SUPERSTRING CAPITAL MANAGEMENT LP 1.75% of their portfolio | 63.2k $2.8m | Reduced -77.9k |
| STEMPOINT CAPITAL LP 0.45% of their portfolio | 59.4k $2.6m | Reduced -13.7k |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 53.4k $2.3m | Added +40.1k |
| SEVEN GRAND MANAGERS, LLC 0.09% of their portfolio | 50.0k $2.2m | Unchanged |
| Point72 Asset Management, L.P. 0.00% of their portfolio | 49.3k $2.2m | Reduced -87.2k |
| TD Asset Management Inc 0.00% of their portfolio | 47.4k $2.1m | Reduced -35.6k |
| ALPS ADVISORS INC 0.01% of their portfolio | 45.5k $2.0m | Added +8.9k |
| SILVERARC CAPITAL MANAGEMENT, LLC 0.21% of their portfolio | 42.5k $1.9m | Added +3.1k |
| Russell Investments Group, Ltd. 0.00% of their portfolio | 42.3k $1.9m | Reduced -6.2k |
| Bank of New York Mellon Corp 0.00% of their portfolio | 41.6k $1.8m | Added +7.8k |
| Nuveen, LLC 0.00% of their portfolio | 41.3k $1.8m | Added +17.5k |
| XTX Topco Ltd 0.02% of their portfolio | 38.1k $1.7m | Added +14.5k |
| WELLINGTON MANAGEMENT GROUP LLP 0.00% of their portfolio | 37.4k $1.6m | Reduced -8.7k |
| MUTUAL OF AMERICA CAPITAL MANAGEMENT LLC 0.02% of their portfolio | 36.0k $1.6m | New |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE 0.00% of their portfolio | 35.4k $1.6m | Reduced -29.0k |
| BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio | 31.8k $1.4m | Reduced -8.8k |
| Swiss National Bank 0.00% of their portfolio | 27.0k $1.2m | New |
| Quadrature Capital Ltd 0.01% of their portfolio | 26.0k $1.1m | New |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 25.4k $1.0m | Added +9.0k |
| Trexquant Investment LP 0.01% of their portfolio | 23.8k $1.0m | New |
| NEW YORK STATE COMMON RETIREMENT FUND 0.00% of their portfolio | 23.6k $1.0m | Added +18.3k |
| TUDOR INVESTMENT CORP ET AL 0.00% of their portfolio | 22.6k $993.1k | New |
| RHUMBLINE ADVISERS 0.00% of their portfolio | 22.3k $981.4k | Added +4.0k |
| Maven Securities LTD 0.09% of their portfolio | 20.0k $879.8k | Reduced -5.0k |
| LOS ANGELES CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 18.6k $820.2k | Added +14.5k |
| Susquehanna Portfolio Strategies, LLC 0.01% of their portfolio | 18.0k $793.3k | New |
| Rafferty Asset Management, LLC 0.00% of their portfolio | 18.0k $792.0k | Reduced -4.1k |
| Shay Capital LLC 0.09% of their portfolio | 18.0k $791.8k | New |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 16.8k $740.0k | Added +10.9k |
| Engineers Gate Manager LP 0.01% of their portfolio | 15.6k $686.4k | New |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio | 14.9k $653.3k | Added +14.0k |
| KENNEDY CAPITAL MANAGEMENT LLC 0.01% of their portfolio | 12.6k $555.2k | Added +337 |
| MARSHALL WACE, LLP 0.00% of their portfolio | 12.6k $554.2k | New |
| Invesco Ltd. 0.00% of their portfolio | 12.4k $546.3k | Added +1.6k |
| MetLife Investment Management, LLC 0.00% of their portfolio | 11.0k $482.7k | Added +2.4k |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC 0.00% of their portfolio | 10.6k $467.3k | Added +10.5k |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.00% of their portfolio | 10.6k $463.4k | Added +1.4k |
| Jump Financial, LLC 0.00% of their portfolio | 10.5k $460.7k | New |
| VANGUARD ASSET MANAGEMENT, Ltd 0.00% of their portfolio | 9.5k $419.4k | New |
| PROFUND ADVISORS LLC 0.01% of their portfolio | 9.1k $402.1k | Reduced -799 |
| Virtus Investment Advisers, LLC 0.09% of their portfolio | 9.1k $400.7k | Added +2.7k |
| Legal & General Group Plc 0.00% of their portfolio | 9.0k $397.8k | Added +7.6k |
| Vanguard Global Advisers, LLC 0.00% of their portfolio | 7.9k $345.4k | Reduced -3.3k |
| China Universal Asset Management Co., Ltd. 0.02% of their portfolio | 7.2k $316.1k | Reduced -734 |
| Quarry LP 0.05% of their portfolio | 6.8k $296.9k | Added +446 |