CYTOMX THERAPEUTICS INC CTMX
COM · Common Stock · CUSIP 23284F105 · ISIN US23284F1057
Company in South San Francisco, United States
- SectorHealth care
- IndustryPharmaceutical Preparations
- HeadquartersSouth San Francisco, CA
- Founded2008
- Websitecytomx.com
- FilingsSEC EDGAR
* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once ($302.3k this quarter). Holder counts are more reliable. Shares outstanding: 217.7m as of 2026-04-30, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $4.70. Options: 10 managers hold calls ($13.3m notional), 6 hold puts ($12.7m).
Trends to Q1 2026
Institutional holders
Managers reporting a position, each quarter
Numbers
| Quarter | Holders |
|---|---|
| Q3 2022 | 85 |
| Q4 2022 | 81 |
| Q1 2023 | 77 |
| Q2 2023 | 68 |
| Q3 2023 | 63 |
| Q4 2023 | 69 |
| Q1 2024 | 89 |
| Q2 2024 | 75 |
| Q3 2024 | 70 |
| Q4 2024 | 71 |
| Q1 2025 | 67 |
| Q2 2025 | 84 |
| Q3 2025 | 103 |
| Q4 2025 | 122 |
| Q1 2026 | 179 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q2 2024 | 42 | 51 |
| Q3 2024 | 27 | 36 |
| Q4 2024 | 32 | 31 |
| Q1 2025 | 27 | 36 |
| Q2 2025 | 56 | 29 |
| Q3 2025 | 61 | 37 |
| Q4 2025 | 71 | 46 |
| Q1 2026 | 128 | 47 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q2 2025 | $2.1m | $362.1k | 0.17 |
| Q3 2025 | $6.8m | $1.0m | 0.15 |
| Q4 2025 | $6.1m | $359.5k | 0.06 |
| Q1 2026 | $13.3m | $12.7m | 0.95 |
Biggest buyers
| BANK OF AMERICA CORP /DE/ | Added | +9.3m |
| FMR LLC | Added | +7.3m |
| Kynam Capital Management, LP | Added | +6.0m |
| CITADEL ADVISORS LLC | Added | +5.1m |
| Nextech Invest Ltd. | New | +4.4m |
| Elmind Capital, LP | Added | +3.9m |
| WELLINGTON MANAGEMENT GROUP LLP | New | +3.6m |
| Siren, L.L.C. | New | +3.5m |
| MILLENNIUM MANAGEMENT LLC | Added | +3.4m |
| Jefferies Financial Group Inc. | Added | +3.0m |
Biggest sellers
| Commodore Capital LP | Sold out | -7.7m |
| Venrock Adviser, LLC | Reduced | -5.6m |
| Financial Engines Advisors L.L.C. | Sold out | -3.8m |
| ORBIMED ADVISORS LLC | Sold out | -3.5m |
| Ikarian Capital, LLC | Sold out | -3.2m |
| Balyasny Asset Management L.P. | Reduced | -3.1m |
| Vivo Capital, LLC | Sold out | -2.9m |
| STEMPOINT CAPITAL LP | Sold out | -1.0m |
| GOLDMAN SACHS GROUP INC | Reduced | -1.0m |
| BOOTHBAY FUND MANAGEMENT, LLC | Reduced | -879.7k |
Biggest calls
| Caption Management, LLC | New | $4.2m900.0k shares |
| BARCLAYS PLC | New | $3.3m700.0k shares |
| DIADEMA PARTNERS LP | New | $1.5m316.0k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $1.4m302.5k shares |
| Stonepine Capital Management, LLC | New | $940.0k200.0k shares |
| CITADEL ADVISORS LLC | Added | $642.0k136.6k shares |
| GROUP ONE TRADING LLC | Added | $526.4k112.0k shares |
| SIMPLEX TRADING, LLC | Added | $506.7k107.8k shares |
| JANE STREET GROUP, LLC | Reduced | $204.0k43.4k shares |
| Persistent Asset Partners Ltd | New | $14.0k801 shares |
Biggest puts
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $4.3m907.8k shares |
| GROUP ONE TRADING LLC | Added | $3.0m628.6k shares |
| Caption Management, LLC | New | $2.0m420.0k shares |
| CITADEL ADVISORS LLC | Added | $1.7m356.4k shares |
| SIMPLEX TRADING, LLC | Added | $1.5m311.9k shares |
| JANE STREET GROUP, LLC | New | $317.7k67.6k shares |
Options at notional value: the value of the shares the contracts control, as filers report them, not what the options cost. Not included in the holders, shares or buying above.
Major shareholders (over 5%)
Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.
| Holder | Stake |
|---|---|
| FMR LLC 13G · institution +2.2 pts · filed 2026-02-05 | 14.6% |
| Kynam Capital Management, LP 13G · institution +3.1 pts · filed 2026-08-14 | 10.0% |
| BlackRock, Inc. 13G · institution new · filed 2026-07-27 | 7.6% |
| Longitude Capital Partners V, LLC 13G · passive investor -0.3 pts · filed 2026-05-15 | 7.0% |
| BANK OF AMERICA CORP /DE/ 13G · institution -1.6 pts · filed 2026-10-28 | 5.4% |
| STATE STREET CORP 13G · institution new · filed 2026-08-07 | 5.4% |
Fell to 5% or below in the last year: Point72 Asset Management, L.P. (3.6%, 2026-08-14), Venrock Healthcare Capital Partners III, L.P. (4.6%, 2026-05-15), Seven Fleet Capital Management LP (0.5%, 2026-05-15), PERCEPTIVE ADVISORS LLC (4.6%, 2026-05-15), VANGUARD GROUP INC (0.0%, 2026-03-26), TANG CAPITAL MANAGEMENT LLC (0.0%, 2026-02-17), ORBIMED ADVISORS LLC (2.1%, 2026-02-17)
Insider purchases and sales in Q1 2026
Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.
Officers and directors buying vs selling
Number of people, by quarter (10% owners not included)
Numbers
| Quarter | Buying | Bought | Selling | Sold | Sold under a plan |
|---|---|---|---|---|---|
| Q2 2024 | 0 | — | 0 | — | — |
| Q3 2024 | 0 | — | 5 | $24.7k | — |
| Q4 2024 | 0 | — | 0 | — | — |
| Q1 2025 | 0 | — | 5 | $48.0k | — |
| Q2 2025 | 0 | — | 3 | $220.1k | — |
| Q3 2025 | 0 | — | 0 | — | — |
| Q4 2025 | 0 | — | 1 | $462.1k | $462.1k |
| Q1 2026 | 0 | — | 4 | $1.2m | $763.8k |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2026-03-17 | McCarthy Sean A. CEO, director | Sold plan | $763.8k119.0k shares |
| 2026-03-17 | BELVIN MARCIA SVP, Chief Scientific Officer | Sold | $202.2k31.5k shares |
| 2026-03-17 | Chu Yu-Waye Chief Medical Officer | Sold | $136.6k21.3k shares |
| 2026-03-17 | Ogden Christopher Chief Financial Officer | Sold | $124.1k19.3k shares |
Their holding: how much the trade added to or took from the insider's holding (direct, or the trust or fund named). The same trade is sometimes reported by more than one insider, such as a fund and the director who represents it; totals count it once. A value is left blank where the reported price is far from the market price (usually a typo).
Holders, Q1 2026
| Manager | Shares | Change |
|---|---|---|
| FMR LLC 0.01% of their portfolio | 32.0m $150.2m | Added +7.3m |
| Kynam Capital Management, LP 4.48% of their portfolio | 15.0m $70.6m | Added +6.0m |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 10.2m $48.0m | Added +9.3m |
| PERCEPTIVE ADVISORS LLC 0.94% of their portfolio | 10.1m $47.5m | Added +418.6k |
| Venrock Adviser, LLC 1.75% of their portfolio | 10.0m $46.9m | Reduced -5.6m |
| VANGUARD CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 8.7m $41.0m | First filing |
| Point72 Asset Management, L.P. 0.06% of their portfolio | 7.9m $37.0m | Added +2.7m |
| STATE STREET CORP 0.00% of their portfolio | 5.7m $26.6m | Added +522.5k |
| CITADEL ADVISORS LLC 0.02% of their portfolio | 5.4m $25.4m | Added +5.1m |
| BlackRock, Inc. 0.00% of their portfolio | 5.2m $24.6m | Added +1.6m |
| BAKER BROS. ADVISORS LP 0.13% of their portfolio | 5.0m $23.4m | Added +725.0k |
| Elmind Capital, LP 6.07% of their portfolio | 4.5m $21.4m | Added +3.9m |
| Nextech Invest Ltd. 1.47% of their portfolio | 4.4m $20.9m | New |
| MARSHALL WACE, LLP 0.02% of their portfolio | 4.1m $19.4m | Added +3.0m |
| MILLENNIUM MANAGEMENT LLC 0.01% of their portfolio | 3.7m $17.2m | Added +3.4m |
| WELLINGTON MANAGEMENT GROUP LLP 0.00% of their portfolio | 3.6m $16.8m | New |
| Siren, L.L.C. 0.45% of their portfolio | 3.5m $16.3m | New |
| ADAR1 Capital Management, LLC 0.96% of their portfolio | 3.4m $16.0m | Reduced -772.6k |
| Eversept Partners, LP 0.99% of their portfolio | 3.2m $15.0m | Added +681.4k |
| UBS Group AG 0.00% of their portfolio | 3.1m $14.7m | Added +2.7m |
| Jefferies Financial Group Inc. 0.18% of their portfolio | 3.1m $14.4m | Added +3.0m |
| TWO SIGMA INVESTMENTS, LP 0.01% of their portfolio | 2.7m $12.7m | Added +1.1m |
| Qube Research & Technologies Ltd 0.02% of their portfolio | 2.2m $10.6m | Added +1.2m |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 2.1m $9.7m | Added +540.9k |
| Woodline Partners LP 0.04% of their portfolio | 2.0m $9.4m | Reduced -336.2k |
| DIMENSIONAL FUND ADVISORS LP 0.00% of their portfolio | 1.9m $9.1m | Added +641.3k |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.01% of their portfolio | 1.9m $8.8m | Added +888.0k |
| GOLDMAN SACHS GROUP INC 0.00% of their portfolio | 1.5m $6.9m | Reduced -1.0m |
| GILDER GAGNON HOWE & CO LLC 0.06% of their portfolio | 1.1m $5.3m | New |
| VANGUARD FIDUCIARY TRUST CO 0.00% of their portfolio | 1.1m $5.2m | First filing |
| Patient Square Capital LP 0.91% of their portfolio | 1.1m $5.1m | New |
| Seven Fleet Capital Management LP 1.60% of their portfolio | 1.1m $5.1m | Added +1.0m |
| JANE STREET GROUP, LLC 0.01% of their portfolio | 997.5k $4.7m | Added +390.3k |
| EVENTIDE ASSET MANAGEMENT, LLC 0.07% of their portfolio | 900.0k $4.2m | New |
| Ally Bridge Group (NY) LLC 4.20% of their portfolio | 900.0k $4.2m | New |
| Trexquant Investment LP 0.03% of their portfolio | 898.8k $4.2m | New |
| VANGUARD PORTFOLIO MANAGEMENT LLC 0.00% of their portfolio | 794.8k $3.7m | First filing |
| Balyasny Asset Management L.P. 0.01% of their portfolio | 730.8k $3.4m | Reduced -3.1m |
| DV Trading LLC 0.30% of their portfolio | 714.0k $3.4m | New |
| NORTHERN TRUST CORP 0.00% of their portfolio | 612.1k $2.9m | Added +197.0k |
| BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio | 606.3k $2.8m | Added +603.5k |
| Ensign Peak Advisors, Inc 0.01% of their portfolio | 592.5k $2.8m | New |
| Caption Management, LLC 0.13% of their portfolio | 573.2k $2.7m | New |
| FIRST TRUST ADVISORS LP 0.00% of their portfolio | 568.6k $2.7m | Added +145.4k |
| Informed Momentum Co LLC 0.31% of their portfolio | 565.1k $2.7m | Added +361.3k |
| Longaeva Partners L.P. 0.12% of their portfolio | 550.0k $2.6m | New |
| Velan Capital Investment Management LP 1.59% of their portfolio | 540.0k $2.5m | Added +460.0k |
| Exome Asset Management LLC 1.44% of their portfolio | 521.5k $2.5m | Reduced -223.8k |
| MORGAN STANLEY 0.00% of their portfolio | 520.5k $2.4m | Added +119.3k |
| SCHULHOFF & CO INC 0.92% of their portfolio | 477.6k $2.2m | Added +102.7k |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 463.4k $2.2m | New |
| 683 Capital Management, LLC 0.19% of their portfolio | 425.0k $2.0m | New |
| RAYMOND JAMES FINANCIAL INC 0.00% of their portfolio | 380.2k $1.8m | Added +63.2k |
| Assenagon Asset Management S.A. 0.00% of their portfolio | 364.2k $1.7m | Reduced -228.5k |
| SEVEN GRAND MANAGERS, LLC 0.10% of their portfolio | 325.0k $1.5m | New |
| Swiss National Bank 0.00% of their portfolio | 319.6k $1.5m | New |
| Soleus Capital Management, L.P. 0.06% of their portfolio | 300.0k $1.4m | New |
| Bank of New York Mellon Corp 0.00% of their portfolio | 289.9k $1.4m | Reduced -38.4k |
| HighVista Strategies LLC 0.37% of their portfolio | 288.1k $1.4m | Added +94.1k |
| Brevan Howard Capital Management LP 0.01% of their portfolio | 269.2k $1.3m | Added +257.8k |
| SIMPLEX TRADING, LLC 0.04% of their portfolio | 248.4k $1.2m | Added +224.4k |
| SEI INVESTMENTS CO 0.00% of their portfolio | 248.2k $1.2m | Added +124.1k |
| Tidal Investments LLC 0.00% of their portfolio | 245.8k $1.2m | Added +200.0k |
| Squarepoint Ops LLC 0.00% of their portfolio | 241.2k $1.1m | Added +191.3k |
| Rafferty Asset Management, LLC 0.00% of their portfolio | 239.8k $1.1m | Reduced -33.8k |
| LMR Partners LLP 0.01% of their portfolio | 234.9k $1.1m | New |
| Scientech Research LLC 0.90% of their portfolio | 230.6k $1.1m | New |
| DAFNA Capital Management LLC 0.25% of their portfolio | 230.0k $1.1m | New |
| Tema ETFs LLC 0.07% of their portfolio | 227.5k $1.1m | New |
| Burkehill Global Management, LP 0.05% of their portfolio | 225.0k $1.1m | New |
| SPHERA FUNDS MANAGEMENT LTD. 0.18% of their portfolio | 220.0k $1.0m | New |
| Stonepine Capital Management, LLC 0.83% of their portfolio | 200.0k $940.0k | New |
| Centiva Capital, LP 0.04% of their portfolio | 200.0k $940.0k | New |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC 0.00% of their portfolio | 189.4k $890.2k | New |
| Y-Intercept (Hong Kong) Ltd 0.01% of their portfolio | 167.5k $787.3k | New |
| GROUP ONE TRADING LLC 0.02% of their portfolio | 154.1k $724.4k | New |
| AWM Investment Company, Inc. 0.08% of their portfolio | 150.0k $705.0k | New |
| BARCLAYS PLC 0.00% of their portfolio | 142.4k $669.3k | Reduced -194.1k |
| Legal & General Group Plc 0.00% of their portfolio | 141.9k $666.9k | New |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 128.8k $605.3k | Added +60.1k |
| VANGUARD ASSET MANAGEMENT, Ltd 0.00% of their portfolio | 122.9k $577.6k | First filing |
| LPL Financial LLC 0.00% of their portfolio | 122.6k $576.4k | Added +9.2k |
| PRELUDE CAPITAL MANAGEMENT, LLC 0.04% of their portfolio | 121.9k $573.0k | Reduced -84.6k |
| NLB Skladi, upravljanje premozenja, d.o.o. 0.03% of their portfolio | 111.1k $522.2k | Added +11.1k |
| CANADA PENSION PLAN INVESTMENT BOARD 0.00% of their portfolio | 108.8k $511.4k | Added +4.6k |
| ALPS ADVISORS INC 0.00% of their portfolio | 105.8k $497.4k | New |
| Jain Global LLC 0.01% of their portfolio | 104.8k $492.3k | Added +83.5k |
| PROFUND ADVISORS LLC 0.02% of their portfolio | 104.5k $491.3k | Added +5.9k |
| Aspire Growth Partners LLC 0.33% of their portfolio | 102.3k $480.6k | Unchanged |
| Virtu Financial LLC 0.02% of their portfolio | 101.9k $479.0k | New |
| CITIGROUP INC 0.00% of their portfolio | 101.8k $478.5k | Added +5.5k |
| Cannon Global Investment Management, LLC 1.09% of their portfolio | 96.1k $451.7k | New |
| LANDSCAPE CAPITAL MANAGEMENT, L.L.C. 0.03% of their portfolio | 94.2k $442.9k | New |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio | 88.4k $415.4k | New |
| Hudson Bay Capital Management LP 0.00% of their portfolio | 80.7k $379.1k | Added +29.7k |
| XTX Topco Ltd 0.01% of their portfolio | 77.9k $365.9k | Added +29.9k |
| Miller Financial Services LLC 0.38% of their portfolio | 72.0k $338.4k | Added +4.0k |
| Vanguard Global Advisers, LLC 0.00% of their portfolio | 71.6k $336.6k | First filing |
| JACOBS LEVY EQUITY MANAGEMENT, INC 0.00% of their portfolio | 68.4k $321.4k | New |
| Schonfeld Strategic Advisors LLC 0.00% of their portfolio | 67.7k $318.3k | New |