Quick Takeaways
- Atlas Venture Fund XI, L.P. filed SCHEDULE 13D/A for SIONNA THERAPEUTICS, INC. Common Stock (SION).
- Disclosed ownership: 5.4%.
- Date of event: 16 Oct 2025.
Atlas Venture Fund XI, L.P. - 16 Oct 2025 SCHEDULE 13D/A Report for SIONNA THERAPEUTICS, INC. Common Stock (SION)
- Filing Manager
- Atlas Venture Fund XI, L.P.
- Reporting Manager
- Atlas Venture Fund XI, L.P.
- Symbol
- SION
- Shares outstanding
- 44,120,278 shares
- Disclosed Ownership
- 2,382,495 shares
- Ownership
- 5.4%
- Form type
- SCHEDULE 13D/A
- Filing time
- 20 Oct 2025, 21:40:43 UTC
- Date of event
- 16 Oct 2025
- Previous filing
- 18 Feb 2025
- SEC
- View on sec.gov
Quoteable Key Fact
"Atlas Venture Fund XI, L.P. disclosed 5.4% ownership in SIONNA THERAPEUTICS, INC. Common Stock (SION) on 16 Oct 2025."
What Changed
- Previous schedule filing date: 18 Feb 2025.
- Current filing was accepted on 20 Oct 2025, 21:40.
Why This Matters
- This page explains what this Schedule 13D/13G filing tells you before manager-level rows.
- You can verify ownership claims directly against the original SEC filing.
Source Evidence
Backed by Schedule 13D/13G
See Original Filing
Beneficial ownership values are sourced from the original SEC Schedule 13D/13G filing.
Reporting Managers (6)
| Name | Ownership | Shares Owned | sole voting power | shared voting power | Signature | Title | CIK |
|---|---|---|---|---|---|---|---|
| Atlas Venture Fund XI, L.P. | 5.4% | 2,382,495 | 0 | 2,382,495 | /s/ Ommer Chohan | Atlas Venture Associates XI, L.P., its GP, By Atlas Venture Associates XI, LLC, its GP, By: Ommer Chohan, CFO | 0001708269 |
| Atlas Venture Associates XI, L.P. | 5.4% | 2,382,495 | 0 | 2,382,495 | /s/ Ommer Chohan | Atlas Venture Associates XI, LLC, its GP, By: Ommer Chohan, CFO | 0001780068 |
| Atlas Venture Associates XI, LLC | 5.4% | 2,382,495 | 0 | 2,382,495 | /s/ Ommer Chohan | Ommer Chohan, CFO | 0001780067 |
| Atlas Venture Opportunity Fund II, L.P. | 1.6% | 701,985 | 0 | 701,985 | /s/ Ommer Chohan | Atlas Venture Associates Opportunity II, L.P., its GP, By: Atlas Venture Associates Opportunity II, LLC, its GP, By: Ommer Chohan, CFO | 0001885327 |
| Atlas Venture Associates Opportunity II, LP | 1.6% | 701,985 | 0 | 701,985 | /s/ Ommer Chohan | Atlas Venture Associates Opportunity II, LLC, its GP, By: Ommer Chohan, CFO | 0001935814 |
| Atlas Venture Associates Opportunity II, LLC | 1.6% | 701,985 | 0 | 701,985 | /s/ Ommer Chohan | By: Ommer Chohan, CFO | 0001935810 |