Summit Therapeutics Inc. (SMMT) Shareholders & Insider Trades
Summit Therapeutics shareholders at a glance
The largest holder of Summit Therapeutics stock is Robert Duggan73.22 %, with 584.1 million shares (73.22% of the company), worth about $7.96 billion as of September 25, 2026. The 10 largest holders together own 90.1%.
In Q2 2026, 272 institutional holdings reports listed 136.0 million shares worth $1.98 billion, up 14.3% in shares from Q1 2026.
Insiders reported 13 transactions in the last two years: no sales and 5 purchases. The newest one on file is from October 21, 2025 (Duggan Robert William, Chief Executive Officer).
Major holders as of September 25, 2026; quarterly totals from institutional holdings reports (latest Q2 2026); insider transactions on file through October 21, 2025.
Summit Therapeutics Inc.
Shareholders Summary
2026Q2
Ownership by Type
Geographic Distribution
Largest Summit Therapeutics shareholders
| Holder | Shares | % of company | Value |
|---|---|---|---|
| Robert Duggan73.22 % | 584.1 million | 73.22% | $8.0B |
| Baker Bros. Advisors LP | 32.8 million | 4.11% | $447.0M |
| Michelle Xia4.018 % | 32.1 million | 4.02% | $437.0M |
| Mahkam Zanganeh3.251 % | 25.9 million | 3.25% | $353.0M |
| Fidelity Management & Research Co. LLC | 10.0 million | 1.26% | $137.0M |
| State Street Corporation | 9.5 million | 1.20% | $130.0M |
| BlackRock Advisors LLC | 8.5 million | 1.07% | $116.0M |
| Vanguard Capital Management LLC | 5.7 million | 0.72% | $78.0M |
| UBS Financial Services, Inc. | 5.2 million | 0.66% | $71.0M |
| Vanguard Portfolio Management LLC | 5.0 million | 0.63% | $69.0M |
As of September 25, 2026.
Summit Therapeutics institutional holdings by quarter
| Quarter | Reports | Shares | Value |
|---|---|---|---|
| Q2 2026 | 272 | 136.0 million | $2.0B |
| Q1 2026 | 242 | 119.0 million | $2.3B |
| Q4 2025 | 225 | 118.0 million | $2.1B |
| Q3 2025 | 261 | 103.0 million | $2.1B |
| Q2 2025 | 256 | 98.1 million | $2.1B |
| Q1 2025 | 236 | 99.0 million | $1.9B |
| Q4 2024 | 234 | 92.6 million | $1.7B |
| Q3 2024 | 198 | 84.6 million | $1.9B |
Shares and value held by institutions that file quarterly holdings reports (options not included).
Summit Therapeutics insider trades
| Insider | Date | Title | Transaction | Value |
|---|---|---|---|---|
| Duggan Robert William | Oct 21, 2025 | Chief Executive Officer | Stock Award(Grant) at price 18.74 per share. | $267.0M |
| Zanganeh Mahkam | Oct 21, 2025 | Chief Executive Officer | Stock Award(Grant) at price 18.74 per share. | $267.0M |
| Soni Manmeet Singh | Oct 21, 2025 | Chief Operating Officer | Stock Award(Grant) at price 18.74 per share. | $999,985 |
| Anand Bhaskar | Oct 21, 2025 | Officer | Stock Award(Grant) at price 18.74 per share. | $499,983 |
| Duggan Robert William | Oct 21, 2025 | Chief Executive Officer | Purchase at price 18.74 per share. | $499,983 |
| Zanganeh Mahkam | Oct 21, 2025 | Chief Executive Officer | Purchase at price 18.74 per share. | $499,983 |
| Xia Yu | Oct 21, 2025 | Director | Purchase at price 18.74 per share. | $10.0M |
| Duggan Robert William | Sep 11, 2025 | Chief Executive Officer | Purchase at price 17.68 - 18.07 per share. | $6.0M |
| Zanganeh Mahkam | Sep 11, 2025 | Chief Executive Officer | Purchase at price 17.68 - 18.07 per share. | $6.0M |
| Duggan Robert William | May 30, 2025 | Chief Executive Officer | Conversion of Exercise of derivative security at price 2.64 per share. | $196,799 |
| Zanganeh Mahkam | May 30, 2025 | Chief Executive Officer | Conversion of Exercise of derivative security at price 2.64 per share. | $196,799 |
| Duggan Robert William | Apr 8, 2025 | Chief Executive Officer | Conversion of Exercise of derivative security at price 1.58 per share. | $6.3M |
Newest 12 of 13 insider transactions in the last two years.
Questions and answers
Who owns the most Summit Therapeutics stock?
Robert Duggan73.22 %, with 73.22% of the company (as of September 25, 2026). Next: Baker Bros. Advisors LP (4.11%) and Michelle Xia4.018 % (4.02%).
How many institutions own Summit Therapeutics stock?
272 institutional holdings reports listed Summit Therapeutics shares in Q2 2026, 136.0 million shares in all worth $1.98 billion.
Are Summit Therapeutics insiders buying or selling the stock?
In the last two years insiders reported no sales and 5 purchases (13 transactions in all); the newest on file is from October 21, 2025.
