As of September 29, 2026, the three largest insider holders of MBRX are Walter V Klemp (Ceo And President, 564.34K shares), Jonathan P. Foster (Chief Financial Officer, 305.67K shares), Donald H Picker (Chief Science Officer, 174.09K shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Walter V Klemp | Ceo And President | 564,340 | 0 | 564,340 | 54.0% | 05 Aug, 2026 |
| 2 | Jonathan P. Foster | Chief Financial Officer | 305,673 | 0 | 305,673 | 29.3% | 05 Aug, 2026 |
| 3 | Donald H Picker | Chief Science Officer | 174,086 | 0 | 174,086 | 16.7% | 05 Aug, 2026 |
| 4 | Robert E. George | Director | 163 | 0 | 163 | 0.0% | 27 Dec, 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 |
|---|---|---|---|---|---|---|---|---|
| 03 Aug, 2026 | Walter V Klemp | Ceo And President | Acquired P | 533,333 | — | — | 564,340 | Direct |
| 03 Aug, 2026 | Jonathan P. Foster | Chief Financial Officer | Acquired P | 293,333 | — | — | 305,673 | Direct |
| 03 Aug, 2026 | Donald H Picker | Chief Science Officer | Acquired P | 173,333 | — | — | 174,086 | Direct |
| 03 Aug, 2026 | Donald H Picker | Chief Science Officer | Acquired P | 519,999 | — | — | 539,595 | Direct |
| 03 Aug, 2026 | Jonathan P. Foster | Chief Financial Officer | Acquired P | 879,999 | — | — | 1,027,717 | Direct |
| 03 Aug, 2026 | Walter V Klemp | Ceo And President | Acquired A | 1,599,999 | — | — | 1,926,335 | Direct |
| 20 Jun, 2026 | Jonathan P. Foster | Chief Financial Officer | Acquired M | 109 | — | — | 12,238 | Direct |
| 20 Jun, 2026 | Donald H Picker | Chief Science Officer | Acquired M | 44 | — | — | 716 | Direct |
| 20 Jun, 2026 | Walter V Klemp | Ceo And President | Acquired M | 150 | — | — | 30,765 | Direct |
| 20 Jun, 2026 | Jonathan P. Foster | Chief Financial Officer | Disposed F | 31 | $2.88 | $89 | 12,207 | Direct |
| 20 Jun, 2026 | Walter V Klemp | Ceo And President | Disposed F | 37 | $2.88 | $107 | 30,728 | Direct |
| 20 Jun, 2026 | Donald H Picker | Chief Science Officer | Disposed F | 13 | $2.88 | $37 | 703 | Direct |
| 22 Jun, 2026 | Jonathan P. Foster | Chief Financial Officer | Acquired M | 174 | — | — | 12,381 | Direct |
| 22 Jun, 2026 | Donald H Picker | Chief Science Officer | Acquired M | 71 | — | — | 774 | Direct |
| 22 Jun, 2026 | Walter V Klemp | Ceo And President | Acquired M | 360 | — | — | 31,088 | Direct |
| 22 Jun, 2026 | Walter V Klemp | Ceo And President | Disposed F | 88 | $3.12 | $275 | 31,007 | Direct |
| 22 Jun, 2026 | Jonathan P. Foster | Chief Financial Officer | Disposed F | 41 | $3.12 | $128 | 12,340 | Direct |
| 22 Jun, 2026 | Donald H Picker | Chief Science Officer | Disposed F | 21 | $3.12 | $66 | 753 | Direct |
| 20 Jun, 2026 | Jonathan P. Foster | Chief Financial Officer | Disposed M | 109 | $0.00 | $0 | 147,892 | Direct |
| 20 Jun, 2026 | Walter V Klemp | Ceo And President | Disposed M | 150 | $0.00 | $0 | 326,696 | Direct |