As of November 6, 2026, one holder's latest Schedule 13D or 13G filing report owning 5% or more of Mustang Bio, Inc. The largest reported stake is Fortress Biotech, Inc.'s, at 8%. 3 filings are on record since August 12, 2025 (Schedule 13D/A, January 5, 2026).
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Key facts
- · Holder: Fortress Biotech, Inc. · Percent: 8% · SCHEDULE 13D/A
- · Holder: Fortress Biotech, Inc. · Percent: 4% · SCHEDULE 13D/A
- · Holder: Mitchell P. Kopin · Percent: 4.99% · SCHEDULE 13G/A
Mustang Bio, Inc. has 3 Schedule 13D or 13G filings on record since 2025-08-12. 1 holder's latest filing reports 5% or more of common stock, $0.0001 par value. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| Fortress Biotech, Inc. | 8% | 537,243 | SCHEDULE 13D/A, 2026-01-05 | 2026-01-02 |
| 4.99% | 185,527 | SCHEDULE 13G/A, 2025-08-12 | 2025-06-30 |
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Keep reading
More on Mustang Bio, Inc. and the records around it.
Mustang Bio, Inc. elsewhere on the record
Companies that share a holder
- Fortress Biotech, Inc. also filed stake reports on 1 other company: Avenue Therapeutics, Inc. (Jan 2026)
- Mitchell P. Kopin also filed stake reports on 55 other companies: SCWorx Corp. (Sep 2026), NFT Limited (Aug 2026), Silexion Therapeutics Corp (Aug 2026)
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Purpose of Transaction (Item 4)
Fortress Biotech, Inc.
The Reporting Person is party to that certain Second Amended and Restated Founders Agreement with the Issuer (as amended, the "Founders Agreement"), in connection with the Issuer's formation. Pursuant to the Issuer's Amended and Restated Certificate of Incorporation (as amended, the "Charter"), the Issuer issues annually to the Reporting Person shares of common stock equal to two and one-half percent (2.5%) of the fully-diluted outstanding equity of the Issuer, as measured as of the date of such issuance (the "Annual Equity Grant"). The foregoing description of the Charter and Founders Agreement are qualified in its entirety by reference to the full text of the Charter and Founders Agreement which are incorporated herein by reference as Exhibits 7.01, 7.02, and 7.04.Item 4 of the SCHEDULE 13D/A filed 2026-01-05
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-08-12 | Mitchell P. Kopin | 4.99% | SCHEDULE 13G/A |
| 2025-10-01 | Fortress Biotech, Inc. | 4% | SCHEDULE 13D/A |
| 2026-01-05 | Fortress Biotech, Inc. | 8% | SCHEDULE 13D/A |
Questions about who owns Mustang Bio, Inc.
Who owns Mustang Bio, Inc.?
On this page, one holder's latest ownership filing reports 5% or more of Mustang Bio, Inc.: Fortress Biotech, Inc. (8%, Schedule 13D/A, filed 2026-01-05).
When did Fortress Biotech, Inc. buy into Mustang Bio, Inc.?
The filings give report dates, not purchase dates. The earliest filing from Fortress Biotech, Inc. on this page is the Schedule 13D/A, filed 2025-10-01, reporting 4%; its latest, Schedule 13D/A filed 2026-01-05, reports 8%. That earliest filing is itself an amendment, which updates an earlier report.
Is this an audit or a full list?
Neither. The ownership list on this page covers only Schedule 13D and 13G filings, which holders make once they own 5% or more of a class of shares (an amendment can report a stake that has since fallen below 5%); 3 such filings are shown here. It is not an audit and not a full cap table: holders who never reached 5% are not listed, and a stake can change after its latest filing.
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Where this comes from
Anyone who comes to own more than 5% of a class of a listed company's voting shares has to tell the SEC. A holder who may seek to change or influence the company files Schedule 13D, and has to say in Item 4, "Purpose of Transaction", what it intends to do. A holder with no such intent, such as many index and passive funds, may file the shorter Schedule 13G. Both are amended when the stake changes, including when it falls below 5%.
Every row here is one of those filings, linked to the filing itself. Percentages and share counts are exactly as the holder filed them, for the holder the filing names; an amendment showing a lower figure is shown as filed. Item 4 text is quoted word for word. Where a 13D's Item 4 contains a sentence stating a definite intent to influence the company, that sentence is marked and quoted; the page does not describe the holder or its motives beyond the words it filed. Nothing here is investment advice.