MBIO's three largest insider shareholders as of September 09, 2026 are Biotech, Inc. Fortress (TenPercentOwner, 536.58K shares), Michael J Zelefsky (Director, 104.20K shares), Michael J Zelefsky (Director, 18.97K shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Biotech, Inc. Fortress | TenPercentOwner | 536,577 | 0 | 536,577 | 79.8% | 05 Jan, 2026 |
| 2 | Michael J Zelefsky | Director | 123,167 | 0 | 123,167 | 18.3% | 07 Jul, 2023 |
| 3 | Brian Achenbach | Svp, Fin. Corp. Controller | 9,649 | 0 | 9,649 | 1.4% | 16 Dec, 2021 |
| 4 | Manuel Md Litchman | President, Ceo And Interim Cfo | 1,874 | 0 | 1,874 | 0.3% | 27 Apr, 2026 |
| 5 | Adam J. Chill | Director | 375 | 0 | 375 | 0.1% | 30 Dec, 2025 |
| 6 | David Jin | Director | 286 | 0 | 286 | 0.0% | 30 Dec, 2025 |
| 7 | Neil Herskowitz | Director | 145 | 0 | 145 | 0.0% | 30 Dec, 2025 |
| 8 | Lindsay A Md Rosenwald | Director | 81 | 0 | 81 | 0.0% | 07 Jul, 2023 |
| 9 | Michael S Weiss | Director | 0 | 66 | 66 | 0.0% | 07 Jul, 2023 |
Each row is that insider’s most recently reported position, from Form 4 filings over the last 60 months — which is why this total does not tie to the quarterly series above, where a quarter counts only the insiders who filed in it. Shares held through a fund or institutional portfolio are counted on the institutional ownership page instead.
| Date | Insider | Position | Transaction | Shares | Price | Value | Shares Held After | Ownership |
|---|---|---|---|---|---|---|---|---|
| 24 Apr, 2026 | Manuel Md Litchman | President, Ceo And Interim Cfo | Disposed F | 19 | $0.75 | $14 | 1,615 | Direct |
| 02 Jan, 2026 | Biotech, Inc. Fortress | TenPercentOwner | Acquired A | 278,385 | $0.00 | $0 | 536,577 | Direct |
| 30 Dec, 2025 | Neil Herskowitz | Director | Disposed S | 247 | $0.96 | $238 | 145 | Direct |
| 30 Dec, 2025 | David Jin | Director | Acquired P | 247 | $0.96 | $238 | 286 | Direct |
| 30 Dec, 2025 | Adam J. Chill | Director | Disposed S | 4 | $0.95 | $4 | 375 | Direct |
| 29 Sep, 2025 | Biotech, Inc. Fortress | TenPercentOwner | Acquired A | 59,334 | $0.00 | $0 | 258,192 | Direct |
| 24 Apr, 2025 | Manuel Md Litchman | President, Ceo And Interim Cfo | Disposed F | 27 | $1.24 | $33 | 1,634 | Direct |
| 31 Mar, 2025 | Biotech, Inc. Fortress | TenPercentOwner | Acquired A | 67,806 | $0.00 | $0 | 198,858 | Direct |
| 27 Jun, 2024 | Biotech, Inc. Fortress | TenPercentOwner | Acquired A | 575,191 | $0.00 | $0 | 3,337 | Direct |
| 31 May, 2024 | Manuel Md Litchman | President And Ceo | Disposed F | 1,396 | $262.49 | $366.43K | 111 | Direct |
| 02 Jan, 2024 | Biotech, Inc. Fortress | TenPercentOwner | Acquired A | 419,092 | $0.00 | $0 | 2,571 | Direct |
| 05 Jul, 2023 | Adam J. Chill | Director | Acquired A | 7,246 | $0.00 | $0 | 26 | Direct |
| 24 Apr, 2023 | Manuel Md Litchman | President And Ceo | Acquired A | 5,000 | $0.00 | $0 | 148 | Direct |
| 05 Jul, 2023 | Michael J Zelefsky | Director | Acquired A | 7,246 | $0.00 | $0 | 18,970 | Direct |
| 05 Jul, 2023 | Lindsay A Md Rosenwald | Director | Acquired A | 7,246 | $0.00 | $0 | 81 | Direct |
| 05 Jul, 2023 | Michael J Zelefsky | Director | Acquired A | 7,246 | $0.00 | $0 | 18,970 | Direct |
| 05 Jul, 2023 | Michael J Zelefsky | Director | Acquired A | 7,246 | $0.00 | $0 | 18,970 | Direct |
| 05 Jul, 2023 | Neil Herskowitz | Director | Acquired A | 7,246 | $0.00 | $0 | 26 | Direct |
| 05 Jul, 2023 | Michael S Weiss | Director | Acquired A | 7,246 | $0.00 | $0 | 66 | Indirect |
| 05 Jul, 2023 | Michael J Zelefsky | Director | Acquired A | 7,246 | $0.00 | $0 | 25 | Direct |