Definium Therapeutics, Inc.
Ownership
Ownership Structure
Who owns Definium Therapeutics, Inc. (DFTX)? This page shows the largest institutions and funds, the ownership structure and the latest insider transactions. 92.9% of the shares are freely tradable; institutional investors hold 65.6%.
Largest Shareholders
Institutions
| Name | Stake (%) | Shares | Change (%) | Date |
|---|---|---|---|---|
| BlackRock Inc | 6.31 | 8,480,230 | +2.5 | 03/31/2026 |
| Driehaus Capital Management LLC | 4.40 | 5,911,889 | -9.6 | 03/31/2026 |
| Capital World Investors | 3.99 | 5,367,723 | +0.0 | 06/30/2026 |
| venBio Select Advisor LLC | 3.72 | 5,000,000 | +0.0 | 03/31/2026 |
| HHG PLC | 2.65 | 3,556,041 | +47.4 | 03/31/2026 |
| Capital Research & Mgmt Co - Division 3 | 2.21 | 2,963,410 | +0.0 | 06/30/2026 |
| Octagon Capital Advisors LP | 2.20 | 2,950,000 | +20.9 | 06/30/2026 |
| Wellington Management Company LLP | 2.20 | 2,949,734 | +126.1 | 06/30/2026 |
Funds
| Name | Stake (%) | Shares | Change (%) | Date |
|---|---|---|---|---|
| American Funds SMALLCAP World A | 5.72 | 7,689,008 | +0.0 | 06/30/2026 |
| iShares Russell 2000 ETF | 2.48 | 3,334,132 | -0.6 | 08/31/2026 |
Largest reported positions according to regulatory filings; stake as a percentage of shares outstanding, change versus the previous filing. Source: fundamentals data.
Insider holdings
| Person | Role | Shares | Value | As of | Type |
|---|---|---|---|---|---|
| Barrow Robert | Chief Executive Officer | 2,244,640 | 86,867,568 $ | Sep 14, 2026 | direct |
| Karlin Daniel | Chief Medical Officer | 803,699 | 31,103,151 $ | Sep 14, 2026 | direct |
| Sullivan Mark | Chief Legal Officer | 508,279 | 19,670,397 $ | Sep 14, 2026 | direct |
| Roberts Brandi | Chief Financial Officer | 397,905 | 15,398,924 $ | Sep 14, 2026 | direct |
| Wiley Matthew T. | Chief Commercial Officer | 362,133 | 14,014,547 $ | Sep 14, 2026 | direct |
Holdings as of each person's most recent SEC Form 4 filing — excluding options and RSUs, which are not shares yet. Holdings may have changed between two filings.
Insiders
Insider Transactions
| Date | Person | Role | Type | Shares | Price | Value |
|---|---|---|---|---|---|---|
| Sep 14, 2026 | Karlin Daniel | Chief Medical Officer | Other | 200,000 | 0.00 | – |
| Sep 14, 2026 | Wiley Matthew T. | Chief Commercial Officer | Other | 125,000 | 0.00 | – |
| Sep 14, 2026 | Sullivan Mark | Chief Legal Officer | Other | 125,000 | 0.00 | – |
| Sep 14, 2026 | Roberts Brandi | Chief Financial Officer | Other | 125,000 | 0.00 | – |
| Sep 14, 2026 | Barrow Robert | Chief Executive Officer | Other | 750,000 | 0.00 | – |
| Sep 3, 2026 | Barrow Robert | Chief Executive Officer | Sell | 19,023 | 37.94 | 721,733 |
| Sep 2, 2026 | Barrow Robert | Chief Executive Officer | Other | 40,000 | 0.00 | – |
| Aug 12, 2026 | Barrow Robert | Chief Executive Officer | Other | 375,000 | 0.00 | – |
| Aug 12, 2026 | Karlin Daniel | Chief Medical Officer | Other | 100,000 | 0.00 | – |
| Aug 12, 2026 | Sullivan Mark | Chief Legal Officer | Other | 62,500 | 0.00 | – |
| Aug 12, 2026 | Wiley Matthew T. | Chief Commercial Officer | Other | 62,500 | 0.00 | – |
| Aug 12, 2026 | Roberts Brandi | Chief Financial Officer | Other | 62,500 | 0.00 | – |
Reportable transactions by officers and major shareholders from SEC Form 4 filings. "Other" includes things like stock grants and option exercises without a buy/sell character. View all insider transactions →
Data as of: September 17, 2026 · Source: fundamental data & SEC filings (annual and quarterly reports, 10-K/10-Q)
Note: pure fact-based analysis, not investment advice and not a solicitation to buy or sell. All figures without guarantee.