Sionna Therapeutics (SION)
Develops NBD1-stabilizing and complementary CFTR modulators for cystic fibrosis.
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Develops small-molecule cystic fibrosis therapies that stabilize NBD1 and pair with complementary CFTR modulators. SION-719 is no longer advancing as an add-on after missing its Phase 2a activity endpoint; next steps for the preferred SION-451 and SION-2222 dual combination remain under evaluation, leaving the business pre-commercial and dependent on clinical validation.
Develops small-molecule cystic fibrosis therapies that stabilize NBD1, the CFTR protein domain where the common F508del mutation disrupts folding and channel function. Its portfolio pairs NBD1 stabilizers SION-451 and SION-719 with complementary modulators SION-2222, SION-109, SION-2851, and SION-3067. Structure-guided discovery and a human bronchial epithelial model guide compound selection.
Clinical priorities changed after SION-719 missed the key activity endpoint in its Phase 2a add-on trial and was dropped from that path. A healthy-volunteer trial met safety, tolerability, and pharmacokinetic objectives for SION-451 combinations; SION-451 plus SION-2222 was selected as the preferred dual combination, with next steps under evaluation.
Based in Massachusetts, the business holds worldwide commercial rights but has no product revenue or commercial organization. Progress depends on clinical validation, regulatory approval, licensed complementary-modulator rights, and third-party manufacturing.
Company facts
Target rangeAs of Sep 22, 2026
Latest analyst notes
| Date | Firm | Action | Prior | Current |
|---|---|---|---|---|
| Sep 15, 2026 | Wedbush | Reiterate | Rating: —Target: $5 | Target: $6 |
| Aug 11, 2026 | Guggenheim | Downgrade | ||
| Aug 11, 2026 | Wedbush | Downgrade | ||
| Aug 10, 2026 | BTIG | Downgrade | ||
| Aug 10, 2026 | Guggenheim | Downgrade |
EPSReportedEstimate
RevenueReportedEstimate
Balance sheet, Jun 30, 2026Cash & short-term investments $211.0M · Total debt $8.1M · Total assets $283.2M · Shareholders' equity $265.8M
- Revenue
- $0
- Operating income
- −$32.5M
- Net income
- −$29.9M
No dividends on record.
| Institutions | ≈ 106.37% | 48.09M shares | |
|---|---|---|---|
| 157 holders · as of Jun 30, 2026 · largest filers plus last quarter's tail | |||
| Insiders | 2.04% | 924.1K shares | |
| 4 holders · as of Sep 18, 2026 | |||
| Strategic holders | 8.17% | 3.69M shares | |
| 1 holder · as of Feb 10, 2025 | |||
| Adds to | 116.58% | ||
45.21M company shares as of Sep 23, 2026 · institutions as of Jun 30, 2026 · holders as of their latest filing
This quarter's institutional total failed a plausibility check; shown: the largest filers plus last quarter's remainder.
These groups come from separate filings that can overlap, so they add to 116.58%; nothing is left for Other.
Top shareholders13F · 13D/G · Form 4
| Holder | Stake | Shares | Date |
|---|---|---|---|
Ra Capital Management, L.P.Institution | 21.91% | 9.91M | as of Jun 30, 2026 |
TPG GP A, LLCInstitution | 14.37% | 6.49M | as of Jun 30, 2026 |
Atlas Venture Fund XI, L.P.Strategic10 percent owner | 8.17% | 3.69M | filed Feb 10, 2025 |
Viking Global Investors LPInstitution | 7.07% | 3.20M | as of Jun 30, 2026 |
Atlas Venture Life Science Advisors, LLCInstitution | 6.63% | 3.00M | as of Jun 30, 2026 |
Insider tradesForm 4
| Date | Insider | Role | Shares | Avg price |
|---|---|---|---|---|
| Sep 17, 2026 | Ra Capital Management, L.P. | director, 10 percent owner: | −3,448,811 | $6.33 |
| Jul 7, 2026 | Orbimed Advisors LLC | director | −85,918 | $44.86 |
| Jul 7, 2026 | Peter A. Thompson | director | −85,918 | $44.86 |
| Jul 6, 2026 | Jennifer Fitzpatrick | officer: Chief Legal Officer | −10,250 | $43.60 |
| Jun 30, 2026 | Orbimed Advisors LLC | director | −115,844 | $45.50 |
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Compare
| Company | Price | Change | |||||
|---|---|---|---|---|---|---|---|
| Sionna Therapeutics | $5.73 | −4.82% | $271.8M | — | — | — | — |
| Vertex Pharmaceuticals | $519.63 | +0.90% | $130.71B | 30.0 | 27.0 | 10.4 | +12.5% |
| Arcturus Therapeutics | $14.07 | −2.16% | $408.7M | — | — | 17.2 | −89.5% |
| 4D Molecular Therapeutics | $15.49 | −2.43% | $830.1M | — | — | 9.0 | +25,106.7% |
| Krystal Biotech | $348.75 | −0.61% | $10.34B | 44.0 | 41.1 | 23.5 | +24.1% |
| Intellia Therapeutics | $12.37 | −2.52% | $1.77B | — | — | 29.8 | −46.2% |
| Median | 37.0 | 34.0 | 17.2 | +12.5% |