Sionna Therapeutics
Develops NBD1-stabilizing and complementary CFTR modulators for cystic fibrosis.
$5.89
After-hours close+0.03 (+0.44%)
At close$5.86(−3.30%)
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Breakdown13F · Form 4
Institutions 100.57%Insiders 8.64%
A 13F quarter can total more than the shares outstanding — sub-advisers file the same block twice, and a filer's own share count can be a quarter stale. No split is drawn from it.
Shares outstanding 45.15M · Float 26.61M · 58.9% free float
Institutions13F, as of Mar 31, 2026
121 holders · 45.41M shares · 31 new positions · 71 increased · 30 reduced · 11 closed
| Holder | Shares | % outstanding | Chg q/q | Filed |
|---|---|---|---|---|
| Ra Capital Management, L.P. | 9.91M | 21.94% | 0 | May 15, 2026 |
| TPG GP A, LLC | 6.49M | 14.39% | −250.0K | May 15, 2026 |
| Orbimed Advisors LLC | 3.53M | 7.82% | −31.0K | May 15, 2026 |
| Viking Global Investors LP | 3.20M | 7.08% | 0 | May 15, 2026 |
| Atlas Venture Life Science Advisors, LLC | 3.00M | 6.63% | 0 | May 14, 2026 |
| Enavate Sciences GP, LLC | 2.48M | 5.49% | 0 | May 15, 2026 |
| JPMorgan Chase & Co | 1.47M | 3.24% | +233.2K | May 13, 2026 |
| Jennison Associates LLC | 1.45M | 3.21% | +335.9K | May 6, 2026 |
Beneficial owners13D/G · 5% or more, as filed
| Holder | % of class | Shares | Form | Filed |
|---|---|---|---|---|
| Peter Kolchinskyincl. Rajeev Shah, RA Capital Nexus Fund III, L.P. +2 more | 22.60% | 10.07M | 13D | Nov 7, 2025 ↗ |
| TPG GP A, LLC | 15.20% | 6.68M | 13D | Feb 18, 2025 ↗ |
| Viking Global Investors LP | 7.10% | 3.20M | 13G | May 15, 2026 ↗ |
| OrbiMed Capital GP VIII LLCincl. Orbimed Advisors LLC | 6.60% | 2.97M | 13D | Apr 20, 2026 ↗ |
| Sionna Aggregator, LPincl. Enavate Sciences GP, LLC | 5.60% | 2.48M | 13D | Feb 18, 2025 ↗ |
| Atlas Venture Associates XI, LLCincl. Atlas Venture Opportunity Fund II, L.P., Atlas Venture Associates Opportunity II, LLC +3 more | 5.40% | 2.38M | 13D | Oct 20, 2025 ↗ |
InsidersForm 4
| Insider | Role | Shares | % outstanding | Filed |
|---|---|---|---|---|
| TPG GP A, LLC | 10 percent owner | 6.49M | 14.39% | Jan 26, 2026 |
| Peter A. Thompson | director | 2.47M | 5.47% | Jul 9, 2026 |
| Bruce Booth | director | 686.6K | 1.52% | Oct 21, 2025 |
| Michael Cloonan | director, officer: President & CEO | 547.3K | 1.21% | Oct 22, 2025 |
| Ra Capital Management, L.P. | director, 10 percent owner: | 159.0K | 0.35% | Nov 24, 2025 |
| Elena Ridloff | officer: CFO & Head of Corp. Dev. | 38.5K | 0.09% | Sep 3, 2025 |
2 ten-percent owners hold 10.13M shares by Form 4 — the 13D/G table above shows those stakes, the figure above counts officers and directors only · 1 person has not refiled in the last 18 months (28.4K shares), so they are not in the figure above
Latest trades
| Date | Insider | Type | Shares | Avg price | Owned after |
|---|---|---|---|---|---|
| Jul 7, 2026 | Orbimed Advisors LLCdirector | Sale | 85,918 | $44.86 | 2,469,959 |
| Jul 7, 2026 | Peter A. Thompsondirector | Sale | 85,918 | $44.86 | 2,469,959 |
| Jul 6, 2026 | Jennifer Fitzpatrickofficer: Chief Legal Officer | Sale | 10,250 | $43.60 | 0 |
| Jun 30, 2026 | Orbimed Advisors LLCdirector | Sale | 115,844 | $45.50 | 2,555,877 |
| Jun 30, 2026 | Peter A. Thompsondirector | Sale | 115,844 | $45.50 | 2,555,877 |
| May 27, 2026 | Orbimed Advisors LLCdirector | Sale | 101 | $44.49 | 2,671,721 |
| May 27, 2026 | Peter A. Thompsondirector | Sale | 101 | $44.49 | 2,671,721 |
| May 11, 2026 | Orbimed Advisors LLCdirector | Sale | 184,639 | $46.22 | 2,671,822 |
| May 8, 2026 | Orbimed Advisors LLCdirector | Sale | 59,767 | $44.58 | 2,856,461 |
| May 7, 2026 | Orbimed Advisors LLCdirector | Sale | 48,546 | $44.61 | 2,916,228 |
CongressHouse and Senate disclosures
Not reported.