---
schema_version: "secwatch.filing_event.v1"
accession: "0001213900-26-037476"
form_type: "8-K"
ticker: "OSTX"
cik: "0001795091"
company_name: "OS Therapies Inc"
filed_at: "2026-03-31T23:59:59+00:00"
generated_at: "2026-05-15T08:12:39.840247+00:00"
event_type: "other"
sentiment: "neutral"
materiality_score: 0.2
calibrated_materiality_score: 0.2
confidence: "high"
source: SEC EDGAR
---

# OS Therapies files prospectus supplement for resale of up to 10.5M shares by selling stockholders

## Summary
- Filed prospectus supplement covering resale of up to 10,529,417 shares of common stock by selling stockholders.
- Shares registered under existing S-3 shelf effective August 12, 2025.
- No new shares issued; proceeds go to selling stockholders, not the company.
- Legal opinion of Olshan Frome Wolosky LLP on share legality attached as Exhibit 5.1.

## SEC filing metadata
- accession: 0001213900-26-037476
- form_type: 8-K
- ticker: OSTX
- cik: 0001795091
- company_name: OS Therapies Inc
- filed_at: 2026-03-31T23:59:59+00:00
- event_type: other
- sentiment: neutral
- materiality_score: 0.2
- calibrated_materiality_score: 0.2
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1795091/000121390026037476/0001213900-26-037476-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1795091/000121390026037476/ea0283924-8k_ostherapies.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001213900-26-037476
- JSON: https://secwatch.observer/filing/0001213900-26-037476.json
- Plain text: https://secwatch.observer/filing/0001213900-26-037476.txt

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