CytomX Therapeutics, Inc. (CTMX) Ownership
CTMX ownership summary
as of October 18, 2026- Institutions
- 104.5% of shares outstanding
- Insiders
- 0.57% of shares outstanding
- Shares outstanding
- 217.9M
- Float
- 179.7M shares available to trade
- Short interest
- 21.25% 40.8M shares short
- Days to cover
- 9.26 short interest up 5.6% vs prior month
- Institutions 104.55%
- Insiders 0.57%
CTMX top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | FMR Inc | 15.01% | 32.7M | $74.6M | +759,300 (+2.4%) | June 30, 2026 |
| 2 | Kynam Capital Management, LP | 9.96% | 21.7M | $49.5M | +6.7M (+44.6%) | June 30, 2026 |
| 3 | BlackRock Inc | 8.06% | 17.6M | $40.0M | +12.3M (+235.9%) | June 30, 2026 |
| 4 | Bank of America Corp | 6.92% | 15.1M | $34.4M | +4.9M (+47.8%) | June 30, 2026 |
| 5 | State Street Corp | 5.39% | 11.7M | $26.8M | +6.1M (+107.4%) | June 30, 2026 |
| 6 | Perceptive Advisors LLC | 4.79% | 10.4M | $23.8M | +340,361 (+3.4%) | June 30, 2026 |
| 7 | Vanguard Capital Management, LLC | 3.91% | 8.5M | $19.4M | −207,661 (−2.4%) | June 30, 2026 |
| 8 | Point72 Asset Management, L.P. | 3.58% | 7.8M | $17.8M | −64,357 (−0.8%) | June 30, 2026 |
| 9 | Wellington Management Company LLP | 2.37% | 5.2M | $11.8M | +1.6M (+44.3%) | June 30, 2026 |
| 10 | VR Adviser, LLC | 2.29% | 5.0M | $11.4M | −5.0M (−50.1%) | June 30, 2026 |
| 11 | Baker Bros Advisors LP | 2.28% | 5.0M | $11.3M | — | June 30, 2026 |
| 12 | Geode Capital Management, LLC | 2.15% | 4.7M | $10.7M | +2.6M (+126.4%) | June 30, 2026 |
| 13 | Elmind Capital LP | 2.09% | 4.5M | $10.4M | — | June 30, 2026 |
| 14 | Nextech Invest, Ltd. | 2.04% | 4.4M | $10.1M | — | June 30, 2026 |
| 15 | Two Sigma Investments LLC | 1.90% | 4.1M | $9.4M | +1.4M (+52.5%) | June 30, 2026 |
| 16 | Eversept Partners, LP | 1.63% | 3.6M | $8.1M | +369,983 (+11.6%) | June 30, 2026 |
| 17 | UBS Group AG | 1.59% | 3.5M | $7.9M | +348,204 (+11.2%) | June 30, 2026 |
| 18 | Siren, L.L.C. | 1.59% | 3.5M | $7.9M | — | June 30, 2026 |
| 19 | ADAR1 Capital Management LLC | 1.54% | 3.4M | $7.7M | −45,072 (−1.3%) | June 30, 2026 |
| 20 | Citadel Advisors Llc | 1.43% | 3.1M | $7.1M | −2.3M (−42.5%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 11 holders added 37.4M shares and 5 cut 7.6M.
CTMX top mutual fund and ETF holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Vanguard MStar Total Stk Mkt Idx Invest | 2.86% | 6.2M | $14.2M | — | August 31, 2026 |
| 2 | Fidelity Select Health Care | 2.75% | 6.0M | $13.7M | +1.0M (+20.0%) | August 31, 2026 |
| 3 | State Street® SPDR® S&P® Biotech ETF | 2.35% | 5.1M | $11.7M | −97,650 (−1.9%) | September 30, 2026 |
| 4 | iShares Russell 2000 ETF | 2.24% | 4.9M | $11.1M | −56,256 (−1.1%) | September 30, 2026 |
| 5 | Fidelity Small Cap Growth | 1.82% | 4.0M | $9.1M | — | July 31, 2026 |
| 6 | Strategic Advisers Fidelity US TtlStk | 1.72% | 3.7M | $8.5M | +1.1M (+41.1%) | August 31, 2026 |
| 7 | Fidelity Advisor Health Care I | 1.38% | 3.0M | $6.8M | +500,000 (+20.0%) | August 31, 2026 |
| 8 | Fidelity Select Biotechnology | 1.28% | 2.8M | $6.3M | +7,900 (+0.3%) | August 31, 2026 |
| 9 | Fidelity Advisor Biotechnology I | 1.14% | 2.5M | $5.7M | — | August 31, 2026 |
| 10 | Fidelity Stock Selector Small Cap | 1.12% | 2.5M | $5.6M | — | July 31, 2026 |
| 11 | Fidelity Small Cap Growth K6 | 0.91% | 2.0M | $4.5M | — | July 31, 2026 |
| 12 | Fidelity Small Cap Index | 0.89% | 1.9M | $4.4M | +14,600 (+0.8%) | July 31, 2026 |
| 13 | Fidelity Series Small Cap Opps | 0.80% | 1.7M | $4.0M | — | July 31, 2026 |
| 14 | iShares Biotechnology ETF | 0.68% | 1.5M | $3.4M | −11,256 (−0.8%) | September 30, 2026 |
| 15 | Fidelity VIP Health Care Initial | 0.54% | 1.2M | $2.7M | +320,000 (+37.2%) | August 31, 2026 |
| 16 | Vanguard Russell 2000 ETF | 0.50% | 1.1M | $2.5M | +73,828 (+7.2%) | September 30, 2026 |
| 17 | iShares Russell 2000 Growth ETF | 0.45% | 973K | $2.2M | −1,231 (−0.1%) | September 30, 2026 |
| 18 | Fidelity Stock Selec | 0.42% | 925K | $2.1M | +270,508 (+41.3%) | August 31, 2026 |
| 19 | Fidelity Extended Market Index | 0.41% | 895K | $2.0M | −4,811 (−0.5%) | August 31, 2026 |
| 20 | iShares Russell 2000 Value ETF | 0.37% | 814K | $1.9M | +1,234 (+0.2%) | September 30, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
CTMX insider transactions
latest 4| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2026-03-17 | Christopher Ogden | Sell | $6.42 | 19,323 | $124,054 |
| 2026-03-17 | Marcia Belvin | Sell | $6.42 | 31,492 | $202,179 |
| 2026-03-17 | Sean A Mccarthy | Sell | $6.42 | 118,969 | $763,781 |
| 2026-03-17 | Yu-Waye Chu | Sell | $6.42 | 21,279 | $136,611 |
Reported trades by company officers, directors and other filers (including disclosures by members of Congress where EODHD lists them). "—" where the filing gives no share count.
CTMX shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns CTMX
Institutional investors own 104.5% of CytomX Therapeutics's shares and insiders 0.57%. The largest holder is FMR Inc with 15.01% of the shares (32.7M), as of June 30, 2026. Among the top 20 institutions, 11 added shares and 5 reduced their stake in the latest filings. Short interest is 21.25% of the float, or 9.26 days of average trading volume. The share count rose 387.3% since 2014.
Related: CTMX analyst forecast, CTMX key metrics. See the CTMX stock overview for the latest quote and news.
CTMX ownership FAQ
Who owns the most CytomX Therapeutics stock?
The largest shareholders of CytomX Therapeutics are FMR Inc (15.01%), Kynam Capital Management, LP (9.96%), BlackRock Inc (8.06%), Bank of America Corp (6.92%), State Street Corp (5.39%).
What percentage of CytomX Therapeutics is owned by institutions?
Institutions hold 104.5% of CytomX Therapeutics's shares outstanding; insiders hold 0.57%.
Which funds own CytomX Therapeutics?
The largest fund holders of CytomX Therapeutics are Vanguard MStar Total Stk Mkt Idx Invest (2.86%), Fidelity Select Health Care (2.75%), State Street® SPDR® S&P® Biotech ETF (2.35%), iShares Russell 2000 ETF (2.24%), Fidelity Small Cap Growth (1.82%).
What is CytomX Therapeutics's short interest?
40.8M shares of CytomX Therapeutics were sold short, 21.25% of the float; at the average daily volume it would take 9.26 days to cover.
Are insiders buying or selling CytomX Therapeutics?
Of the latest 4 reported insider transactions in CytomX Therapeutics (since March 17, 2026), 0 were purchases and 4 were sales.
How many shares of CytomX Therapeutics are outstanding?
CytomX Therapeutics has 217.9M shares outstanding, of which 179.7M are in the public float.