Summit Therapeutics's top three insider shareholders as of August 29, 2026 are Mahkam Zanganeh (Co Chief Executive Officer, 599.71Mn shares), Mahkam Zanganeh (Co Chief Executive Officer, 595.88Mn shares), Robert W Duggan (Co Chief Executive Officer, 570.15Mn shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Mahkam Zanganeh | Co Chief Executive Officer | 0 | 599,708,353 | 599,708,353 | 90.7% | 12 Jun, 2026 |
| 2 | Yu Xia | Director | 0 | 32,057,147 | 32,057,147 | 4.8% | 23 Oct, 2025 |
| 3 | Robert W Duggan | Co Chief Executive Officer | 0 | 25,824,474 | 25,824,474 | 3.9% | 04 Jun, 2026 |
| 4 | Manmeet Singh Soni | Coo And Cfo | 3,123,603 | 0 | 3,123,603 | 0.5% | 04 Jun, 2026 |
| 5 | Ankur Dhingra | Chief Financial Officer | 0 | 354,958 | 354,958 | 0.1% | 27 Mar, 2024 |
| 6 | Bhaskar Anand | Chief Accounting Officer | 159,751 | 0 | 159,751 | 0.0% | 23 Oct, 2025 |
| 7 | Jeff Huber | Director | 0 | 44,052 | 44,052 | 0.0% | 13 Sep, 2024 |
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 |
|---|---|---|---|---|---|---|---|---|
| 12 Jun, 2026 | Mahkam Zanganeh | Co Chief Executive Officer | Acquired P | 3,810,000 | $13.12 | $49.99Mn | 573,883,879 | Indirect |
| 04 Jun, 2026 | Manmeet Singh Soni | Coo And Cfo | Acquired P | 25,000 | $14.46 | $361.50K | 3,098,603 | Direct |
| 04 Jun, 2026 | Mahkam Zanganeh | Co Chief Executive Officer | Acquired P | 100,000 | $14.60 | $1.46Mn | 25,824,474 | Indirect |
| 04 Jun, 2026 | Robert W Duggan | Co Chief Executive Officer | Acquired P | 100,000 | $14.60 | $1.46Mn | 25,824,474 | Indirect |
| 04 Jun, 2026 | Manmeet Singh Soni | Coo And Cfo | Acquired P | 25,000 | $14.43 | $360.75K | 3,123,603 | Direct |
| 08 Jan, 2026 | Bhaskar Anand | Chief Accounting Officer | Acquired A | 30,000 | — | — | 30,000 | Direct |
| 02 Jan, 2026 | Mahkam Zanganeh | Co Chief Executive Officer | Acquired A | 11,232 | $8.76 | $98.39K | 11,232 | Indirect |
| 02 Jan, 2026 | Yu Xia | Director | Acquired A | 35,000 | — | — | 35,000 | Direct |
| 02 Jan, 2026 | Robert W Duggan | Co Chief Executive Officer | Acquired A | 11,232 | $8.76 | $98.39K | 11,232 | Direct |
| 02 Jan, 2026 | Yu Xia | Director | Acquired A | 35,000 | — | — | 35,000 | Direct |
| 02 Jan, 2026 | Mahkam Zanganeh | Co Chief Executive Officer | Acquired A | 11,232 | $8.76 | $98.39K | 11,232 | Indirect |
| 02 Jan, 2026 | Jeff Huber | Director | Acquired A | 35,000 | — | — | 35,000 | Direct |
| 02 Jan, 2026 | Robert F. Booth | Director | Acquired A | 35,000 | — | — | 35,000 | Direct |
| 02 Jan, 2026 | Mostafa Ronaghi | Director | Acquired A | 35,000 | — | — | 35,000 | Direct |
| 02 Jan, 2026 | Mahkam Zanganeh | Co Chief Executive Officer | Acquired A | 11,232 | $8.76 | $98.39K | 11,232 | Indirect |
| 02 Jan, 2026 | Yu Xia | Director | Acquired A | 35,000 | — | — | 35,000 | Direct |
| 02 Jan, 2026 | Alessandra Cesano | Director | Acquired A | 35,000 | — | — | 35,000 | Direct |
| 02 Jan, 2026 | Yu Xia | Director | Acquired A | 35,000 | — | — | 35,000 | Direct |
| 02 Jan, 2026 | Mahkam Zanganeh | Co Chief Executive Officer | Acquired A | 11,232 | $8.76 | $98.39K | 11,232 | Indirect |
| 02 Jan, 2026 | Kenneth A Clark | Director | Acquired A | 35,000 | — | — | 35,000 | Direct |