---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-26-390577"
form_type: "8-K"
ticker: "SION"
cik: "0002036042"
company_name: "Sionna Therapeutics, Inc."
filed_at: "2026-09-14T20:10:18+00:00"
generated_at: "2026-09-14T20:11:54.333604+00:00"
event_type: "other_material"
sentiment: "neutral"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Sionna cuts workforce 46%, plans Phase 2a trial for SION-451+SION-2222

## Summary
- Board approved restructuring cutting ~46% of workforce, retaining core clinical capabilities for SION-451 and SION-2222.
- Estimated restructuring charges of ~$6.4M, including $5.3M severance and $0.7M contract close-out for SION-719.
- Chief Business Officer Caroline Stark Beer terminated without cause effective Sept 15, 2026; severance benefits approved.
- Stock options repriced to closing price on Sept 17, 2026 for retained employees; original price reinstated if exercised before 18 months.
- Plans to advance SION-451+SION-2222 into Phase 2a proof-of-concept trial initiating Q1 2027; cash runway extended into H2 2029.

## SEC filing metadata
- accession: 0001193125-26-390577
- form_type: 8-K
- ticker: SION
- cik: 0002036042
- company_name: Sionna Therapeutics, Inc.
- filed_at: 2026-09-14T20:10:18+00:00
- event_type: other_material
- sentiment: neutral
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 2.05, 5.02, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/2036042/000119312526390577/0001193125-26-390577-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/2036042/000119312526390577/d148638d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-26-390577
- JSON: https://secwatch.observer/filing/0001193125-26-390577.json
- Plain text: https://secwatch.observer/filing/0001193125-26-390577.txt

## Key facts
- Executive change
  Jennifer Fitzpatrick changed role as Head of Program Management at Sionna Therapeutics, Inc..
  - Action: assumed
  - Role: Head of Program Management
  source text: Jennifer Fitzpatrick, the Company’s Chief Legal Officer, assumed the additional role of Head of Program Management
  evidence_url: https://www.sec.gov/Archives/edgar/data/2036042/000119312526390577/0001193125-26-390577-index.htm
- Executive change
  Elena Ridloff changed role as Chief Business Officer at Sionna Therapeutics, Inc..
  - Action: assumed
  - Role: Chief Business Officer
  source text: Elena Ridloff, the Company’s Chief Financial Officer, assumed the additional role of Chief Business Officer
  evidence_url: https://www.sec.gov/Archives/edgar/data/2036042/000119312526390577/0001193125-26-390577-index.htm
- Executive change
  Caroline Stark Beer was terminated as Chief Business Officer at Sionna Therapeutics, Inc..
  - Action: terminated
  - Role: Chief Business Officer
  source text: the employment of Caroline Stark Beer, M.B.A., the Company’s Chief Business Officer, was terminated without cause, effective as of September 15, 2026
  evidence_url: https://www.sec.gov/Archives/edgar/data/2036042/000119312526390577/0001193125-26-390577-index.htm
- Executive change
  Charlotte McKee changed role as Head of Research and Development at Sionna Therapeutics, Inc..
  - Action: assumed
  - Role: Head of Research and Development
  source text: Charlotte McKee, the Company’s Chief Medical Officer, assumed the additional role of Head of Research and Development
  evidence_url: https://www.sec.gov/Archives/edgar/data/2036042/000119312526390577/0001193125-26-390577-index.htm

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.