Institutional ownership · Form 13F
SION institutional ownership
Sionna Therapeutics, Inc. - Common Stock: reported institutional holdings as of 2026-06-30 (filed through 2026-08-31), aggregated by StockEyes from SEC Form 13F information tables. SION is one of 2732 tickers in the validated publication set. Mapping coverage in this publication set: 4562 of 6046 universe tickers have at least one validated CUSIP mapping (75.5%). Latest-quarter filed value resolved to any listed ticker: 77.3%; resolved to this universe: 77.2%.
SION: change since the prior quarter's filings
More managers reported a position, with the count rising from 122 in the quarter ended 2026-03-31 to 147 in the quarter ended 2026-06-30 (+25, 20.5%). Total reported shares rose to 48,281,390 (+2,640,466, 5.8%), moving the same way as the manager count. Among the 25 managers listed as top holders in both quarters, the largest increases were ADAGE CAPITAL PARTNERS GP, L.L.C. (+1,450,000 shares) and Siren, L.L.C. (+310,515 shares), among 11 managers who added shares, and the largest decreases were ORBIMED ADVISORS LLC (-974,825 shares) and DEERFIELD MANAGEMENT COMPANY, L.P. (-289,674 shares), among 7 managers who reduced shares. Casdin Capital, LLC (400,000 shares), Driehaus Capital Management LLC (385,447 shares) and 3 more entered the listed top holders; Sio Capital Management, LLC (294,340 shares in the prior quarter), Soleus Capital Management, L.P. (293,500 shares in the prior quarter) and 3 more dropped out of the listed top holders.
New to 13F data? Read how to read a 13F filing, or see where institutions moved overall in the Smart Money Report.
Reported totals, quarter ended 2026-06-30
147 reporting managers held 48,281,390 shares, reported value $2,097,228,119 exactly as filed. Values are position values transcribed from the filings, not current market prices.
Reported quarter-over-quarter change (quarter ended 2026-03-31 to quarter ended 2026-06-30): reporting managers +25, reported shares +2,640,466 (+5.79%), reported value +16.88%. These changes compare two filing snapshots.
Shares outstanding check: 45,306,105 shares reported by the issuer (SEC XBRL, period ended 2026-06-30). Reported 13F shares equal 106.6% of that figure. This page passed the publication sanity gate before listing.
SION in this quarter's filings
Concentration check: the largest reported position, RA CAPITAL MANAGEMENT, L.P. with 9,905,045 shares, is 20.5% of all shares reported for SION this quarter. The five largest reporting managers together account for 52.1% of the reported total, so the headline total is dominated by a handful of large managers.
Reported quarter-over-quarter change: the reporting-manager count rose by 25 versus the quarter ended 2026-03-31, and reported shares moved +5.79% (+2,640,466 shares). That is a comparison of two filing snapshots, not a record of trades on any single day.
Shares-outstanding cross-check: reported 13F shares equal 106.6% of the issuer share count used at the publication gate (45,306,105 shares, issuer period ended 2026-06-30). The gate publishes a ticker only when that relationship is plausible; lending chains can push reported totals above a simple ownership share, which is why the figure is a sanity check and not an ownership percentage.
Largest reporting managers, SION
| # | Manager | Shares | Value as filed | Share of reported total |
|---|---|---|---|---|
| 1 | RA CAPITAL MANAGEMENT, L.P. | 9,905,045 | $435,722,930 | 20.5% |
| 2 | TPG GP A, LLC | 6,494,962 | $285,713,378 | 13.5% |
| 3 | VIKING GLOBAL INVESTORS LP | 3,195,181 | $140,556,012 | 6.6% |
| 4 | Atlas Venture Life Science Advisors, LLC | 2,995,602 | $131,776,532 | 6.2% |
| 5 | ORBIMED ADVISORS LLC | 2,555,877 | $112,433,029 | 5.3% |
| 6 | ENAVATE SCIENCES GP, LLC | 2,478,030 | $109,008,540 | 5.1% |
| 7 | ADAGE CAPITAL PARTNERS GP, L.L.C. | 1,600,000 | $70,384,000 | 3.3% |
| 8 | BlackRock, Inc. | 1,474,769 | $64,875,089 | 3.1% |
| 9 | JPMORGAN CHASE & CO | 1,490,508 | $64,085,673 | 3.1% |
| 10 | JENNISON ASSOCIATES LLC | 1,172,133 | $51,562,131 | 2.4% |
| 11 | CITADEL ADVISORS LLC | 1,147,636 | $50,484,507 | 2.4% |
| 12 | VANGUARD CAPITAL MANAGEMENT LLC | 1,132,001 | $49,796,724 | 2.3% |
| 13 | STATE STREET CORP | 1,021,534 | $44,937,281 | 2.1% |
| 14 | PERCEPTIVE ADVISORS LLC | 905,000 | $39,810,950 | 1.9% |
| 15 | DEERFIELD MANAGEMENT COMPANY, L.P. | 680,916 | $29,953,495 | 1.4% |
Manager names and figures are transcribed from each manager's own Form 13F information table. A manager listing shares in this snapshot does not mean it holds them today.
Reported change, 2026-03-31 to 2026-06-30
| Quarter ended | Filed through | Reporting managers | Reported shares | Value as filed |
|---|---|---|---|---|
| 2026-03-31 | 2026-05-29 | 122 | 45,640,924 | $1,794,286,632 |
| 2026-06-30 | 2026-08-31 | 147 | 48,281,390 | $2,097,228,119 |
Every change figure on this page is a reported quarter-over-quarter change between filing snapshots. It is not real-time trading activity.
SION reported totals over time
Quarter ended 2026-06-30: 147 reporting managers · 48,281,390 reported shares · $2,097,228,119 value as filed.
The full archived series is part of StockEyes Pro. Continue with Google to sign in.
Quarter-end 13F filed data, long positions only; filings arrive up to 45 days after quarter end.
CUSIPs behind the SION total
The validated bridge mapped 1 current CUSIP(s) to SION for this quarter: 829401108. Option pseudo-CUSIPs, units, warrants, and preferred classes are excluded from these common-share totals. Mapping coverage in this publication set: 4562 of 6046 universe tickers have at least one validated CUSIP mapping (75.5%). Latest-quarter filed value resolved to any listed ticker: 77.3%; resolved to this universe: 77.2%.
What this page is and is not
Form 13F reports are quarterly holdings snapshots. Managers file up to about 45 days after quarter-end, so these figures describe reported positions as of the quarter-end date, not holdings today. 13F lists reportable long positions from managers above the SEC reporting threshold and omits short positions entirely.
This page is informational only. It is not investment advice, a recommendation, or a signal to buy or sell. Source: SEC Form 13F bulk data set for filings through 2026-08-31 (period ended 2026-06-30), joined to tickers through StockEyes' validated CUSIP bridge. Methodology and coverage are documented on the institutional ownership hub.
Insider transactions for SION (officer and director buys and sells) are covered by InsiderTrace: insidertrace.com/stock/sion. StockEyes does not duplicate insider transaction tables.
Related StockEyes pages
Latest headlines tagged SION are on the market news wire. Upcoming earnings and market dates are on the events calendar. The term itself is defined in the institutional investor glossary entry, and the research workflow behind pages like this one is walked through in how to research a stock and how to compare SEC filings.