---
schema_version: "secwatch.filing_event.v1"
accession: "0001558370-23-012033"
form_type: "8-K"
ticker: "MBIO"
cik: "0001680048"
company_name: "MUSTANG BIO, INC."
filed_at: "2023-07-20T23:59:59+00:00"
generated_at: "2026-06-13T05:39:08.009446+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.5
calibrated_materiality_score: 0.5
confidence: "high"
source: SEC EDGAR
---

# Mustang Bio downsizes Worcester office; annual rent to drop from ~$583K to ~$246K

## Summary
- Relocation from 26,503 sq ft to 11,916 sq ft on second floor; rent abated until March 1, 2024.
- New annual base rent of $246,312 for rest of 2023, escalating 2% yearly through Jan 2030.
- Sublessor provides $119,160 tenant improvement allowance; must be used by Feb 29, 2024.
- Company vacated existing premises with no holdover liability; not currently occupying any space.

## SEC filing metadata
- accession: 0001558370-23-012033
- form_type: 8-K
- ticker: MBIO
- cik: 0001680048
- company_name: MUSTANG BIO, INC.
- filed_at: 2023-07-20T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.5
- calibrated_materiality_score: 0.5
- confidence: high
- sec_items: 1.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1680048/000155837023012033/0001558370-23-012033-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1680048/000155837023012033/tmb-20230718x8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001558370-23-012033
- JSON: https://secwatch.observer/filing/0001558370-23-012033.json
- Plain text: https://secwatch.observer/filing/0001558370-23-012033.txt

## Key facts
- Material Agreements
  MUSTANG BIO, INC. amended Third Amendment to Sublease with The Paul Revere Life Insurance Company valued at Amendment to sublease relocating premises to 11,916 sq ft on second floor, rent abatement until Marc (effective 2023-06-15).
  - Action: amendment
  - Agreement: lease
  - Counterparty: The Paul Revere Life Insurance Company
  - Value: Amendment to sublease relocating premises to 11,916 sq ft on second floor, rent abatement until Marc
  - Effective: 2023-06-15
  source text: On July 18, 2023, Mustang Bio, Inc. (the “ Company ”) executed, with a retroactive Effective Date of June 15, 2023, the Third Amendment to Sublease (the “ Third Amendment ”), with The Paul Revere Life Insurance Company, a Massachusetts corporation (the “ Sublessor ”), which amends the Sublease, dated June 14, 2022, by and between the Company and the Landlord (the “ Original Sublease ,” and as amended, the “ Sublease ”)
  evidence_url: https://www.sec.gov/Archives/edgar/data/1680048/000155837023012033/0001558370-23-012033-index.htm

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