Definium Therapeutics's three largest insider shareholders as of September 26, 2026 are Robert Barrow (Chief Executive Officer, 2.24Mn shares), Daniel Karlin (Chief Medical Officer, 803.70K shares), Mark Sullivan (Chief Legal Officer, 508.28K shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Robert Barrow | Chief Executive Officer | 2,509,780 | 0 | 2,509,780 | 43.1% | 14 Sep, 2026 |
| 2 | Daniel Karlin | Chief Medical Officer | 1,075,561 | 0 | 1,075,561 | 18.5% | 14 Sep, 2026 |
| 3 | Mark Sullivan | Chief Legal Officer | 508,279 | 0 | 508,279 | 8.7% | 14 Sep, 2026 |
| 4 | Brandi Roberts | Chief Financial Officer | 397,905 | 0 | 397,905 | 6.8% | 14 Sep, 2026 |
| 5 | Matthew T. Wiley | Chief Commercial Officer | 362,133 | 0 | 362,133 | 6.2% | 14 Sep, 2026 |
| 6 | Schond L. Greenway | Chief Financial Officer | 295,728 | 0 | 295,728 | 5.1% | 26 Mar, 2024 |
| 7 | Wernli Miri Halperin | Executive President | 287,409 | 0 | 287,409 | 4.9% | 22 Aug, 2024 |
| 8 | Carrie Liao | Chief Accounting Officer | 171,820 | 0 | 171,820 | 3.0% | 26 Mar, 2025 |
| 9 | Cynthia W. Hu | Chief Legal Officersecretary | 80,004 | 0 | 80,004 | 1.4% | 28 Mar, 2022 |
| 10 | Carol A Vallone | Director | 25,170 | 0 | 25,170 | 0.4% | 18 Sep, 2026 |
| 11 | Roger Crystal | Director | 24,289 | 0 | 24,289 | 0.4% | 15 Jun, 2026 |
| 12 | Suzanne Louise Bruhn | Director | 24,289 | 0 | 24,289 | 0.4% | 15 Jun, 2026 |
| 13 | Andreas Krebs | Director | 22,839 | 0 | 22,839 | 0.4% | 18 Sep, 2026 |
| 14 | David W Gryska | Director | 19,900 | 0 | 19,900 | 0.3% | 15 Jun, 2026 |
| 15 | Brigid Makes | Director | 10,581 | 0 | 10,581 | 0.2% | 06 Jun, 2022 |
| 16 | Roger Adsett | Director | 3,555 | 0 | 3,555 | 0.1% | 15 Jun, 2026 |
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 |
|---|---|---|---|---|---|---|---|---|
| 18 Sep, 2026 | Andreas Krebs | Director | Acquired M | 1,629 | $35.52 | $57.86K | 21,402 | Direct |
| 18 Sep, 2026 | Carol A Vallone | Director | Acquired M | 1,086 | $35.52 | $38.57K | 22,296 | Direct |
| 18 Sep, 2026 | Carol A Vallone | Director | Disposed M | 1,086 | $0.00 | $0 | 0 | Direct |
| 18 Sep, 2026 | Andreas Krebs | Director | Disposed M | 1,629 | $0.00 | $0 | 0 | Direct |
| 02 Sep, 2026 | Robert Barrow | Chief Executive Officer | Acquired A | 40,000 | $0.00 | $0 | 1,513,663 | Direct |
| 03 Sep, 2026 | Robert Barrow | Chief Executive Officer | Disposed S | 19,023 | $37.94 | $721.73K | 1,494,640 | Direct |
| 12 Aug, 2026 | Brandi Roberts | Chief Financial Officer | Acquired A | 62,500 | $0.00 | $0 | 271,987 | Direct |
| 12 Aug, 2026 | Daniel Karlin | Chief Medical Officer | Acquired A | 100,000 | $0.00 | $0 | 603,282 | Direct |
| 12 Aug, 2026 | Robert Barrow | Chief Executive Officer | Acquired A | 375,000 | $0.00 | $0 | 1,473,246 | Direct |
| 12 Aug, 2026 | Mark Sullivan | Chief Legal Officer | Acquired A | 62,500 | $0.00 | $0 | 383,071 | Direct |
| 12 Aug, 2026 | Matthew T. Wiley | Chief Commercial Officer | Acquired A | 62,500 | $0.00 | $0 | 237,133 | Direct |
| 25 Jun, 2026 | Robert Barrow | Chief Executive Officer | Disposed S | 29,208 | $45.03 | $1.32Mn | 1,098,246 | Direct |
| 25 Jun, 2026 | Daniel Karlin | Chief Medical Officer | Disposed S | 10,035 | $45.03 | $451.88K | 503,282 | Direct |
| 25 Jun, 2026 | Matthew T. Wiley | Chief Commercial Officer | Disposed S | 2,867 | $45.03 | $129.10K | 174,633 | Direct |
| 25 Jun, 2026 | Mark Sullivan | Chief Legal Officer | Disposed S | 13,008 | $45.03 | $585.75K | 320,571 | Direct |
| 25 Jun, 2026 | Brandi Roberts | Chief Financial Officer | Disposed S | 3,013 | $45.03 | $135.68K | 209,487 | Direct |
| 22 Jun, 2026 | Robert Barrow | Chief Executive Officer | Acquired A | 375,000 | $0.00 | $0 | 1,127,454 | Direct |
| 22 Jun, 2026 | Brandi Roberts | Chief Financial Officer | Acquired A | 62,500 | $0.00 | $0 | 212,500 | Direct |
| 22 Jun, 2026 | Matthew T. Wiley | Chief Commercial Officer | Acquired A | 62,500 | $0.00 | $0 | 177,500 | Direct |
| 22 Jun, 2026 | Daniel Karlin | Chief Medical Officer | Acquired A | 100,000 | $0.00 | $0 | 513,317 | Direct |