Comparable stake leader
Robert W. Duggan
SEC ownership of Summit Therapeutics Inc.
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0001599298.
Disclosed value leader
Robert W. Duggan
Comparable rows
0/50
Latest evidence
12 Jun 2026
- Public ticker
- SMMT on Nasdaq
- Parsed ownership sources
-
3/4/5 and 13F
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
- Largest SEC-reported holder
-
Robert W. Duggan
Ranking: Comparable ownership first, then disclosed value
- Latest parsed ownership date
-
12 Jun 2026
Freshness: Most recent filing date in this holder set
- Issuer CIK
- 0001599298
- Issuer location
- Miami, FL
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
1 signal
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
Ownership snapshot
Top shareholders of Summit Therapeutics Inc. (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.
Comparable stake leader
Robert W. Duggan
Disclosed value leader
Robert W. Duggan
Comparable rows
0/50
Latest evidence
12 Jun 2026
3/4/5
13F
Highest disclosed value: $8,324,567,933
50 rows are not safely comparable across share classes.
Showing 1-8 of 50 holder rows.
Quick read
Robert W. Duggan has the largest disclosed position value at $8.32B.
0 of 50 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.
Open SEC evidence
Opens Robert W. Duggan's linked filing trail.
Disclosed position value
Top 5
Robert W. Duggan
$8.32B
Mahkam Zanganeh
$8.21B
BAKER BROS. ADVISORS LP
$689.97M
Yu Xia
$600.8M
FMR LLC
$205.78M
Value bars compare disclosed positions; verify each figure against the linked filing evidence.
Detailed SEC evidence table Showing 1-8 of 50 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| Robert W. Duggan |
3/4/5
Co-Chief Executive Officer, Director, 10%+ Owner
|
—
mixed-class rows
|
$8,324,567,933
622,015,239 shares
mixed-class rows
|
+$57,931,939 | 12 Jun 2026 |
| Mahkam Zanganeh |
3/4/5
Co-Chief Executive Officer, Director, 10%+ Owner
|
—
mixed-class rows
|
$8,214,516,275
619,617,599 shares
mixed-class rows
|
+$57,931,939 | 12 Jun 2026 |
| BAKER BROS. ADVISORS LP |
13F
Company
|
—
class O/S missing
|
$689,974,554
36,391,063 shares
|
— | 31 Mar 2026 |
| Yu Xia |
3/4/5
Director
|
—
mixed-class rows
|
$600,800,855
32,092,147 shares
mixed-class rows
|
+$9,999,983 | 02 Jan 2026 |
| FMR LLC |
13F
Company
|
—
class O/S missing
|
$205,776,661
10,853,199 shares
|
— | 31 Mar 2026 |
| BlackRock, Inc. |
13F
Company
|
—
class O/S missing
|
$183,035,250
9,653,758 shares
|
— | 31 Mar 2026 |
| PRICE T ROWE ASSOCIATES INC /MD/ |
13F
Company
|
—
class O/S missing
|
$156,949,000
8,277,859 shares
|
— | 31 Mar 2026 |
| STATE STREET CORP |
13F
Company
|
—
class O/S missing
|
$133,253,914
7,028,160 shares
|
— | 31 Mar 2026 |
How to read this table
Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
Forms 3/4/5 flow
Insider trading overview
Net insider flow leans to buying over the last 12 months. Net value: +$126,586,111.
Buys
$126,586,111
Insiders: 4
Sells
$0
Insiders: 0
Net
+$126,586,111
Shares: +9,133,765
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 9,133,765
Shares: 0
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 7,870,000 | 0 | $103,616,650 | $0 | +$103,616,650 |
| 3-6 | 0 | 0 | $0 | $0 | $0 |
| 6-9 | 0 | 0 | $0 | $0 | $0 |
| 9-12 | 1,263,765 | 0 | $22,969,461 | $0 | +$22,969,461 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-14 of 14 reporting-owner rows connected to Summit Therapeutics Inc.. Open a relationship link for the CIK-to-CIK filing trail.
Rows
14
Largest Forms 3/4/5 holder
Robert W. Duggan
Net 12M change
+$126,586,111
Latest report
12 Jun 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| Robert W. Duggan | Co-Chief Executive Officer, Director, 10%+ Owner | $8,324,567,933 | +$57,931,939 | +0.7% | Mixed | 12 Jun 2026 |
| Mahkam Zanganeh | Co-Chief Executive Officer, Director, 10%+ Owner | $8,214,516,275 | +$57,931,939 | +0.71% | Mixed | 12 Jun 2026 |
| Yu Xia | Director | $600,800,855 | +$9,999,983 | +1.7% | Mixed | 02 Jan 2026 |
| Manmeet Singh Soni | COO and CFO, Director | $46,525,591 | +$722,250 | +1.6% | Mixed | 04 Jun 2026 |
| Bhaskar Anand | Chief Accounting Officer | $3,682,233 | Mixed | 08 Jan 2026 | ||
| Ankur Dhingra | Chief Financial Officer | $1,331,093 | Filing P/S | 26 Mar 2024 | ||
| Urte Gayko | Director | $528,000 | Mixed | 25 Apr 2022 | ||
| Mostafa Ronaghi | Director | $321,300 | Mixed | 02 Jan 2026 | ||
| Kenneth A. Clark | Director | $155,892 | Mixed | 02 Jan 2026 | ||
| Ujwala Mahatme | Director | $115,599 | Mixed | 02 Jan 2024 | ||
| Jeff Huber | Director | $86,592 | Mixed | 02 Jan 2026 | ||
| Robert F. Booth | Director | $62,896 | Mixed | 02 Jan 2026 | ||
| Alessandra Cesano | Director | $28,198 | Mixed | 02 Jan 2026 | ||
| Jeffrey R. Maranian | VP Corporate Controller | $19,800 | Mixed | 15 Dec 2021 |
Recent insider transactions for Summit Therapeutics Inc.
Showing up to 300 recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | SEC-reported value | SEC-reported price | Shares | Shares owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| Mahkam Zanganeh | SMMT | Common Stock | Purchase | 0.67% | $49,987,200 | $13.12 | 3,810,000 | 573,883,879 | 12 Jun 2026 | By Spouse |
| Robert W. Duggan | SMMT | Common Stock | Purchase | 0.67% | $49,987,200 | $13.12 | 3,810,000 | 573,883,879 | 12 Jun 2026 | Direct |
| Robert W. Duggan | SMMT | Common Stock | Purchase | 0.39% | $1,460,000 | $14.60 | 100,000 | 25,824,474 | 04 Jun 2026 | By the Mahkam Zanganeh Revocable Trust, with the Spouse of Reporting Person as Trustee |
| Mahkam Zanganeh | SMMT | Common Stock | Purchase | 0.39% | $1,460,000 | $14.60 | 100,000 | 25,824,474 | 04 Jun 2026 | By the Mahkam Zanganeh Revocable Trust, with the Reporting Person as Trustee |
| Manmeet Singh Soni | SMMT | Common Stock | Purchase | 1.63% | $722,250 | $14.44 | 50,000 | 3,123,603 | 04 Jun 2026 | Direct |
| Bhaskar Anand | SMMT | Stock Option (right to buy) | Award | 30,000 | 30,000 | 08 Jan 2026 | Direct | |||
| Mahkam Zanganeh | SMMT | Stock Option (right to buy) | Award | 11,232 | 11,232 | 02 Jan 2026 | By Spouse | |||
| Robert W. Duggan | SMMT | Stock Option (right to buy) | Award | 11,232 | 11,232 | 02 Jan 2026 | Direct | |||
| Robert F. Booth | SMMT | Stock Option (right to buy) | Award | 42,180 | 35,000 | 02 Jan 2026 | Direct | |||
| Yu Xia | SMMT | Stock Option (right to buy) | Award | 35,000 | 35,000 | 02 Jan 2026 | Direct | |||
| Jeff Huber | SMMT | Stock Option (right to buy) | Award | 44,885 | 35,000 | 02 Jan 2026 | Direct | |||
| Mostafa Ronaghi | SMMT | Stock Option (right to buy) | Award | 35,000 | 35,000 | 02 Jan 2026 | Direct | |||
| Kenneth A. Clark | SMMT | Stock Option (right to buy) | Award | 52,796 | 35,000 | 02 Jan 2026 | Direct | |||
| Alessandra Cesano | SMMT | Stock Option (right to buy) | Award | 38,219 | 35,000 | 02 Jan 2026 | Direct | |||
| Yu Xia | SMMT | Common Stock | Purchase | 1.69% | $9,999,983 | $18.74 | 533,617 | 32,057,147 | 21 Oct 2025 | Akeso, Inc. |
| Bhaskar Anand | SMMT | Common Stock | Award | 20% | 26,680 | 159,751 | 21 Oct 2025 | Direct | ||
| Manmeet Singh Soni | SMMT | Common Stock | Award | 1.77% | 53,361 | 3,073,603 | 21 Oct 2025 | Direct | ||
| Robert W. Duggan | SMMT | Common Stock | Purchase | 53.4% | $499,983 | $18.74 | 26,680 | 76,680 | 21 Oct 2025 | Immediate family member of Spouse |
| Robert W. Duggan | SMMT | Common Stock | Award | 1.05% | 266,808 | 25,724,474 | 21 Oct 2025 | By the Mahkam Zanganeh Revocable Trust, with the Spouse of Reporting Person as Trustee | ||
| Robert W. Duggan | SMMT | Common Stock | Award | 2.51% | 13,980,789 | 570,073,879 | 21 Oct 2025 | Direct | ||
| Mahkam Zanganeh | SMMT | Common Stock | Award | 2.51% | 13,980,789 | 570,073,879 | 21 Oct 2025 | By Spouse | ||
| Mahkam Zanganeh | SMMT | Common Stock | Purchase | 53.4% | $499,983 | $18.74 | 26,680 | 76,680 | 21 Oct 2025 | Immediate family member |
| Mahkam Zanganeh | SMMT | Common Stock | Award | 1.05% | 266,808 | 25,724,474 | 21 Oct 2025 | By the Mahkam Zanganeh Revocable Trust, with the Reporting Person as Trustee | ||
| Bhaskar Anand | SMMT | Stock Option (right to buy) | Award | 50,000 | 50,000 | 18 Sep 2025 | Direct | |||
| Mahkam Zanganeh | SMMT | Common Stock | Purchase | $90,350 | $18.07 | 5,000 | 556,093,090 | 11 Sep 2025 | By Spouse | |
| Robert W. Duggan | SMMT | Common Stock | Purchase | $90,350 | $18.07 | 5,000 | 556,093,090 | 11 Sep 2025 | Direct | |
| Mahkam Zanganeh | SMMT | Common Stock | Purchase | 0.06% | $5,894,406 | $17.68 | 333,394 | 556,088,090 | 10 Sep 2025 | By Spouse |
| Robert W. Duggan | SMMT | Common Stock | Purchase | 0.06% | $5,894,406 | $17.68 | 333,394 | 556,088,090 | 10 Sep 2025 | Direct |
* marks a reported price that did not pass the local price check.