Definium Therapeutics, Inc. (DFTX) shareholders
DFTXNasdaqMedicinal Chemicals & Botanical ProductsFiscal year ends December 31
$32.08−0.92 (-2.79%)
Close on Nov 13, 2026Market cap $4.31BP/E –Yield –
Ownership
Institutional holdings as of Jun 30, 2026, from 13F filings
Held by institutions
85.4%
115M of 134M shares
Institutional holders
360
149 new, 29 sold out
Net institutional buying
40M
In Q2 2026
Insider trades, 12 months
0 buys · 17 sales
Net sold $7.00M
Shares held by institutions
Holders of more than 5%
Latest Schedule 13D (active) or 13G (passive) filed by each holder
| Holder | Shares | % of class | Filing | As of |
|---|---|---|---|---|
| Abigail P. Johnson Joint filing with FMR LLC (6.50%) | 8,791,720 | 6.50% | 13G (passive) | Sep 30, 2026 |
| Michael Kramarz Joint filing with Commodore Capital LP (7.20%), Commodore Capital Master LP (7.20%) and 1 more | 7,428,775 | 7.20% | 13G (passive) amendment | Dec 31, 2025 |
| Driehaus Capital Management LLC | 6,845,276 | 5.36% | 13G (passive) amendment | Jun 30, 2026 |
| BlackRock, Inc. | 6,070,053 | 8.30% | 13G (passive) amendment | Dec 31, 2024 |
| David Kroin Joint filing with Deep Track Capital, LP (5.54%), Deep Track Biotechnology Master Fund, Ltd. (5.54%) | 5,676,540 | 5.54% | 13G (passive) amendment | Dec 31, 2025 |
| Deep Track Biotechnology Master Fund, Ltd. Joint filing with Deep Track Capital, LP (6.87%), David Kroin (6.87%) | 5,500,000 | 6.87% | 13G (passive) amendment | Sep 30, 2025 |
| Behzad Aghazadeh Joint filing with Avoro Capital Advisors LLC (5.08%) | 5,000,000 | 5.08% | 13G (passive) | Dec 31, 2025 |
Top institutional holders
13F holdings as of Jun 30, 2026
| Holder | Shares | % of DFTX | Value | Change | % of portfolio |
|---|---|---|---|---|---|
| BlackRock, Inc. | 11,232,834 | 8.36% | $528.39M | +2,752,604 | 0.01% |
| Avoro Capital Advisors LLC | 7,188,888 | 5.35% | $338.17M | +2,188,888 | 3.04% |
| Driehaus Capital Management LLC | 6,845,276 | 5.09% | $322.00M | +933,387 | 1.87% |
| Jupiter Topco LLC | 5,615,645 | 4.18% | $264.00M | New | 0.11% |
| Capital World Investors | 5,367,723 | 3.99% | $252.50M | New | 0.03% |
| FMR LLC | 4,752,921 | 3.54% | $223.58M | +2,943,311 | 0.01% |
| Price T Rowe Associates Inc /Md/ | 4,652,032 | 3.46% | $218.83M | +4,582,031 | 0.02% |
| Geode Capital Management, LLC | 3,644,813 | 2.71% | $171.48M | +1,149,414 | 0.01% |
| State Street Corp | 3,065,390 | 2.28% | $144.20M | +593,517 | 0.00% |
| Capital International Investors | 2,963,410 | 2.21% | $139.40M | New | 0.03% |
| Octagon Capital Advisors LP | 2,950,000 | 2.20% | $138.77M | +510,000 | 12.47% |
| Wellington Management Group Llp | 2,949,734 | 2.20% | $138.76M | +1,644,985 | 0.02% |
| Deep Track Capital, LP | 2,750,000 | 2.05% | $129.36M | −250,000 | 1.88% |
| Commodore Capital LP | 2,000,000 | 1.49% | $94.08M | – | 5.60% |
| Alliancebernstein L.P. | 1,803,287 | 1.34% | $34.08M | +1,711,584 | 0.01% |
| Goldman Sachs Group Inc | 1,800,852 | 1.34% | $84.71M | +125,441 | 0.01% |
| Citadel Advisors LLC | 1,688,587 | 1.26% | $79.43M | +355,145 | 0.01% |
| Vanguard Portfolio Management LLC | 1,648,426 | 1.23% | $77.54M | +775,761 | 0.00% |
| Ra Capital Management, L.P. | 1,500,000 | 1.12% | $70.56M | New | 0.61% |
| Vanguard Capital Management LLC | 1,486,454 | 1.11% | $69.92M | +389,476 | 0.00% |
Institutional buying and selling by quarter
Positions opened, added to, reduced and closed by 13F filers
| Quarter | Holders | Shares held | % of shares | New / added | Reduced / closed | Shares bought | Shares sold |
|---|---|---|---|---|---|---|---|
| Q2 2026 | 360 | 115M | 85.4% | 149 / 116 | 64 / 29 | 50M | 10M |
| Q1 2026 | 245 | 78M | 58.3% | 238 / 2 | 4 / 1 | 70M | 3M |
| Q4 2025 | 8 | 11M | 8.4% | 8 / 0 | 0 / 0 | 11M | 0M |
Top mutual fund and ETF holders
Latest monthly portfolio reports (Form N-PORT)
| Fund | Shares | % of DFTX | Value | % of fund | As of |
|---|---|---|---|---|---|
| SMALLCAP World Fund Inc | 7,689,008 | 5.72% | $361.69M | 0.38% | Jun 30, 2026 |
| iShares Russell 2000 ETF | 3,347,307 | 2.49% | $157.46M | 0.19% | Jun 30, 2026 |
| Vanguard Extended Market Index Fund | 1,486,832 | 1.11% | $69.94M | 0.07% | Jun 30, 2026 |
| Fidelity Small Cap Index Fund | 1,422,899 | 1.06% | $61.92M | 0.18% | Jul 31, 2026 |
| T. Rowe Price Health Sciences Fund, Inc. | 1,287,318 | 0.96% | $60.56M | 0.51% | Jun 30, 2026 |
| iShares Russell 2000 Growth ETF | 1,188,581 | 0.88% | $55.91M | 0.36% | Jun 30, 2026 |
| T. Rowe Price New Horizons Fund, Inc. | 1,141,178 | 0.85% | $53.68M | 0.36% | Jun 30, 2026 |
| Fidelity Small Cap Growth Fund | 779,396 | 0.58% | $33.92M | 0.39% | Jul 31, 2026 |
| iShares Biotechnology ETF | 743,400 | 0.55% | $34.97M | 0.38% | Jun 30, 2026 |
| Vanguard Health Care Fund | 740,600 | 0.55% | $32.23M | 0.08% | Jul 31, 2026 |
| T. Rowe Price Integrated U.S. Small-Cap Growth Equity Fund | 728,490 | 0.54% | $34.27M | 0.35% | Jun 30, 2026 |
| Janus Henderson Global Life Sciences Fund | 710,241 | 0.53% | $33.41M | 0.58% | Jun 30, 2026 |
| Eventide Healthcare & Life Sciences Fund | 710,000 | 0.53% | $33.40M | 1.87% | Jun 30, 2026 |
| Driehaus Small Cap Growth Fund | 595,284 | 0.44% | $28.00M | 1.74% | Jun 30, 2026 |
| Lord Abbett Developing Growth Fund Inc | 538,017 | 0.40% | $23.41M | 1.05% | Jul 31, 2026 |
Officers, directors and major owners
People who filed Forms 3, 4 or 5 in the last two years
| Name | Role | Shares owned | % of shares | Latest filing |
|---|---|---|---|---|
| Robert Barrow | Chief Executive Officer, Director | 2,213,090 | 1.65% | Sep 29, 2026 |
| Daniel Karlin | Chief Medical Officer, Director | 792,846 | 0.59% | Sep 29, 2026 |
| Mark Sullivan | Chief Legal Officer | 494,228 | 0.37% | Sep 29, 2026 |
| Brandi Roberts | Chief Financial Officer | 394,528 | 0.29% | Sep 29, 2026 |
| Matthew T. Wiley | Chief Commercial Officer | 359,036 | 0.27% | Sep 29, 2026 |
| Carrie Liao | Chief Accounting Officer | 144,923 | 0.11% | Mar 26, 2025 |
| Carol A. Vallone | Director | 22,296 | 0.02% | Sep 18, 2026 |
| Andreas Krebs | Director | 21,402 | 0.02% | Sep 18, 2026 |
| David W. Gryska | Director | 19,900 | 0.01% | Jun 15, 2026 |
| Suzanne Louise Bruhn | Director | 24,289 | 0.02% | Jun 15, 2026 |
| Roger Adsett | Director | 3,555 | 0.00% | Jun 15, 2026 |
| Roger Crystal | Director | 24,289 | 0.02% | Jun 15, 2026 |
Insider trades
Common stock transactions reported on Form 4, newest first
| Insider | Date | Transaction | Shares | Price | Value | Shares after |
|---|---|---|---|---|---|---|
| Matthew T. Wiley Chief Commercial Officer | Sep 25, 2026 | Sale(10b5-1 plan) | −3,097 | $36.57 | $113.26K | 359,036 |
| Brandi Roberts Chief Financial Officer | Sep 25, 2026 | Sale(10b5-1 plan) | −3,377 | $36.57 | $123.50K | 394,528 |
| Mark Sullivan Chief Legal Officer | Sep 25, 2026 | Sale(10b5-1 plan) | −14,051 | $36.57 | $513.85K | 494,228 |
| Daniel Karlin Chief Medical Officer, Director | Sep 25, 2026 | Sale(10b5-1 plan) | −10,853 | $36.57 | $396.89K | 792,846 |
| Robert Barrow Chief Executive Officer, Director | Sep 25, 2026 | Sale(10b5-1 plan) | −31,550 | $36.57 | $1.15M | 2,213,090 |
| Carol A. Vallone Director | Sep 18, 2026 | Option exercise | +1,086 | $35.52 | $38.57K | 22,296 |
| Andreas Krebs Director | Sep 18, 2026 | Option exercise | +1,629 | $35.52 | $57.86K | 21,402 |
| Mark Sullivan Chief Legal Officer | Sep 14, 2026 | Award | +125,000 | – | – | 508,279 |
| Matthew T. Wiley Chief Commercial Officer | Sep 14, 2026 | Award | +125,000 | – | – | 362,133 |
| Daniel Karlin Chief Medical Officer | Sep 14, 2026 | Award | +200,000 | – | – | 803,699 |
| Robert Barrow Chief Executive Officer, Director | Sep 14, 2026 | Award | +750,000 | – | – | 2,244,640 |
| Brandi Roberts Chief Financial Officer | Sep 14, 2026 | Award | +125,000 | – | – | 397,905 |
| Robert Barrow Chief Executive Officer, Director | Sep 3, 2026 | Sale(10b5-1 plan) | −19,023 | $37.94 | $721.73K | 1,494,640 |
| Robert Barrow Chief Executive Officer, Director | Sep 2, 2026 | Award | +40,000 | – | – | 1,513,663 |
| Daniel Karlin Chief Medical Officer | Aug 12, 2026 | Award | +100,000 | – | – | 603,282 |
| Robert Barrow Chief Executive Officer, Director | Aug 12, 2026 | Award | +375,000 | – | – | 1,473,246 |
| Matthew T. Wiley Chief Commercial Officer | Aug 12, 2026 | Award | +62,500 | – | – | 237,133 |
| Mark Sullivan Chief Legal Officer | Aug 12, 2026 | Award | +62,500 | – | – | 383,071 |
| Brandi Roberts Chief Financial Officer | Aug 12, 2026 | Award | +62,500 | – | – | 271,987 |
| Robert Barrow Chief Executive Officer, Director | Jun 25, 2026 | Sale(10b5-1 plan) | −29,208 | $45.03 | $1.32M | 1,098,246 |
| Matthew T. Wiley Chief Commercial Officer | Jun 25, 2026 | Sale(10b5-1 plan) | −2,867 | $45.03 | $129.10K | 174,633 |
| Mark Sullivan Chief Legal Officer | Jun 25, 2026 | Sale(10b5-1 plan) | −13,008 | $45.03 | $585.75K | 320,571 |
| Brandi Roberts Chief Financial Officer | Jun 25, 2026 | Sale(10b5-1 plan) | −3,013 | $45.03 | $135.68K | 209,487 |
| Daniel Karlin Chief Medical Officer | Jun 25, 2026 | Sale(10b5-1 plan) | −10,035 | $45.03 | $451.88K | 503,282 |
| Matthew T. Wiley Chief Commercial Officer | Jun 22, 2026 | Award | +62,500 | – | – | 177,500 |
| Mark Sullivan Chief Legal Officer | Jun 22, 2026 | Award | +62,500 | – | – | 333,579 |
| Daniel Karlin Chief Medical Officer | Jun 22, 2026 | Award | +100,000 | – | – | 513,317 |
| Brandi Roberts Chief Financial Officer | Jun 22, 2026 | Award | +62,500 | – | – | 212,500 |
| Robert Barrow Chief Executive Officer, Director | Jun 22, 2026 | Award | +375,000 | – | – | 1,127,454 |
| Roger Crystal Director | Jun 11, 2026 | Award | +4,666 | – | – | 24,289 |
| Andreas Krebs Director | Jun 11, 2026 | Award | +4,666 | – | – | 19,773 |
| Carol A. Vallone Director | Jun 11, 2026 | Award | +4,666 | – | – | 21,210 |
| Suzanne Louise Bruhn Director | Jun 11, 2026 | Award | +4,666 | – | – | 24,289 |
| David W. Gryska Director | Jun 11, 2026 | Award | +4,666 | – | – | 19,900 |
| Roger Adsett Director | Jun 11, 2026 | Award | +3,555 | – | – | 3,555 |
| Robert Barrow Chief Executive Officer, Director | Mar 25, 2026 | Sale(10b5-1 plan) | −24,431 | $18.47 | $451.24K | 752,454 |
| Daniel Karlin Chief Medical Officer | Mar 25, 2026 | Sale(10b5-1 plan) | −8,018 | $18.47 | $148.09K | 413,317 |
| Mark Sullivan Chief Legal Officer | Mar 25, 2026 | Sale(10b5-1 plan) | −10,702 | $18.47 | $197.67K | 271,079 |
| Robert Barrow Chief Executive Officer, Director | Feb 3, 2026 | Award | +320,000 | – | – | 1,098,477 |
| Daniel Karlin Chief Medical Officer | Feb 3, 2026 | Award | +150,000 | – | – | 575,025 |
| Mark Sullivan Chief Legal Officer | Feb 3, 2026 | Award | +125,000 | – | – | 407,576 |
| Matthew T. Wiley Chief Commercial Officer | Feb 3, 2026 | Award | +115,000 | – | – | 115,000 |
| Brandi Roberts Chief Financial Officer | Feb 3, 2026 | Award | +150,000 | – | – | 150,000 |
| Robert Barrow Chief Executive Officer, Director | Dec 26, 2025 | Sale(10b5-1 plan) | −25,791 | $13.15 | $339.15K | 778,477 |
| Mark Sullivan Chief Legal Officer | Dec 26, 2025 | Sale(10b5-1 plan) | −11,276 | $13.15 | $148.28K | 282,576 |
| Daniel Karlin Chief Medical Officer | Dec 26, 2025 | Sale(10b5-1 plan) | −5,600 | $13.15 | $73.64K | 425,025 |
| Mark Sullivan Chief Legal Officer | Sep 25, 2025 | Sale(10b5-1 plan) | −11,278 | $9.77 | $110.19K | 293,852 |
| Robert Barrow Chief Executive Officer, Director | Sep 25, 2025 | Sale(10b5-1 plan) | −25,797 | $9.77 | $252.04K | 804,268 |
| Daniel Karlin Chief Medical Officer | Sep 25, 2025 | Sale(10b5-1 plan) | −7,704 | $9.77 | $75.27K | 430,625 |
| Mark Sullivan Chief Legal Officer | Jun 25, 2025 | Sale(10b5-1 plan) | −11,491 | $6.80 | $78.14K | 305,130 |
| Daniel Karlin Chief Medical Officer | Jun 25, 2025 | Sale(10b5-1 plan) | −7,848 | $6.80 | $53.37K | 438,329 |
| Robert Barrow Chief Executive Officer, Director | Jun 25, 2025 | Sale(10b5-1 plan) | −26,491 | $6.80 | $180.14K | 830,065 |
| Daniel Karlin Chief Medical Officer | Mar 25, 2025 | Sale(10b5-1 plan) | −6,836 | $6.74 | $46.07K | 446,177 |
| Mark Sullivan Chief Legal Officer | Mar 25, 2025 | Sale(10b5-1 plan) | −6,576 | $6.74 | $44.32K | 316,621 |
| Robert Barrow Chief Executive Officer, Director | Mar 25, 2025 | Sale(10b5-1 plan) | −21,208 | $6.74 | $142.94K | 856,556 |
| Carrie Liao Chief Accounting Officer | Mar 25, 2025 | Sale(10b5-1 plan) | −2,347 | $6.74 | $15.82K | 144,923 |
| Robert Barrow Chief Executive Officer, Director | Mar 12, 2025 | Award | +350,000 | – | – | 877,764 |
| Carrie Liao Chief Accounting Officer | Mar 12, 2025 | Award | +50,000 | – | – | 142,270 |
| Mark Sullivan Chief Legal Officer | Mar 12, 2025 | Award | +150,000 | – | – | 323,197 |
| Daniel Karlin Chief Medical Officer | Mar 12, 2025 | Award | +115,000 | – | – | 453,013 |
Awards, option exercises, tax withholding and gifts are shown alongside open-market buys and sales. Each name links to the filing on SEC EDGAR.
Short interest
Shares sold short and not yet bought back, as of Oct 30, 2026 (FINRA, reported twice a month)
Short % of float
7.40%
10M shares short
Days to cover
5.8
At 2M shares a day
Change since last report
-4.3%
From 10M shares
Short volume, 20 days
69.7%
Of volume reported to FINRA
Shares sold short, last 10 months
Short sale volume counts trades marked short on any given day, including market-maker hedging, so it runs far higher than the share of Definium Therapeutics's stock actually held short. Settlement fails (shares not delivered on time) peaked at 24,417 shares on Oct 9, 2026 over the last 90 days.
Planned insider sales
Notices of proposed sale filed on Form 144 before shares are sold
| Seller | Filed | Shares | Market value | Planned sale | Acquired through |
|---|---|---|---|---|---|
| Mark Sullivan Officer | Sep 25, 2026 | 14,051 | $516.09K | Sep 25, 2026 | Restricted Stock Vesting Under a Registered Plan |
| Brandi Roberts Officer | Sep 25, 2026 | 3,377 | $124.04K | Sep 25, 2026 | Restricted Stock Vesting Under a Registered Plan |
| Matthew T. Wiley Officer | Sep 25, 2026 | 3,097 | $113.75K | Sep 25, 2026 | Restricted Stock Vesting Under a Registered Plan |
| Daniel Karlin Officer | Sep 25, 2026 | 10,853 | $398.63K | Sep 25, 2026 | Restricted Stock Vesting Under a Registered Plan |
| Robert Barrow Officer, Director | Sep 25, 2026 | 31,550 | $1.16M | Sep 25, 2026 | Restricted Stock Vesting Under a Registered Plan |
| Robert Barrow Officer, Director | Sep 3, 2026 | 19,023 | $718.14K | Sep 3, 2026 | Performance Stock Units |
| Robert Barrow Officer, Director | Jun 25, 2026 | 29,208 | $1.23M | Jun 25, 2026 | Restricted Stock Vesting Under a Registered Plan |
| Daniel Karlin Officer | Jun 25, 2026 | 10,035 | $422.77K | Jun 25, 2026 | Restricted Stock Vesting Under a Registered Plan |
| Brandi Roberts Officer | Jun 25, 2026 | 3,013 | $126.94K | Jun 25, 2026 | Restricted Stock Vesting Under a Registered Plan |
| Mark Sullivan Officer | Jun 25, 2026 | 13,008 | $548.03K | Jun 25, 2026 | Restricted Stock Vesting Under a Registered Plan |
| Matthew T. Wiley Officer | Jun 25, 2026 | 2,867 | $120.79K | Jun 25, 2026 | Restricted Stock Vesting Under a Registered Plan |
| Mark Sullivan Officer | Mar 25, 2026 | 10,702 | $197.67K | Mar 25, 2026 | Restricted stock vesting under a registered plan |
| Daniel Karlin Officer | Mar 25, 2026 | 8,018 | $148.09K | Mar 25, 2026 | Restricted stock vesting under a registered plan |
| Robert Barrow Officer, Director | Mar 25, 2026 | 24,431 | $451.24K | Mar 25, 2026 | Restricted stock vesting under a registered plan |
| Mark Sullivan Officer | Dec 29, 2025 | 11,276 | $148.24K | Dec 26, 2025 | Restricted Stock Vesting |
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