---
schema_version: "secwatch.filing_event.v1"
accession: "0001558370-23-006343"
form_type: "8-K"
ticker: "MBIO"
cik: "0001680048"
company_name: "MUSTANG BIO, INC."
filed_at: "2023-04-20T23:59:59+00:00"
generated_at: "2026-06-16T22:35:35.478589+00:00"
event_type: "other"
sentiment: "neutral"
materiality_score: 0.3
calibrated_materiality_score: 0.3
confidence: "high"
source: SEC EDGAR
---

# Mustang Bio amends ATM equity program; up to $100M authorized, ~$8M remaining

## Summary
- Amendment No. 3 to At Market Issuance Sales Agreement dated April 14, 2023.
- Total ATM offering capacity remains $100M; ~$92M already sold, ~$8M available.
- Adds Instruction I.B.6 limitations based on non-affiliate market cap; removes Oppenheimer & Co. as agent.
- No securities sold under Instruction I.B.6 in prior 12 months; program continues under existing registration.

## SEC filing metadata
- accession: 0001558370-23-006343
- form_type: 8-K
- ticker: MBIO
- cik: 0001680048
- company_name: MUSTANG BIO, INC.
- filed_at: 2023-04-20T23:59:59+00:00
- event_type: other
- sentiment: neutral
- materiality_score: 0.3
- calibrated_materiality_score: 0.3
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1680048/000155837023006343/0001558370-23-006343-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1680048/000155837023006343/tmb-20230414x8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001558370-23-006343
- JSON: https://secwatch.observer/filing/0001558370-23-006343.json
- Plain text: https://secwatch.observer/filing/0001558370-23-006343.txt

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