CytomX Therapeutics, Inc.
US ˙ NasdaqGS ˙ US23284F1057

SecurityCTMX / CytomX Therapeutics, Inc.
InstitutionCitadel Advisors Llc
ManagerKen Griffin
Latest Disclosed Ownership5,406,193 shares
Latest Disclosed Value $ 25,409,107
Citadel Advisors Llc ownership in CTMX / CytomX Therapeutics, Inc.

On May 15, 2026 - Citadel Advisors Llc filed a 13F-HR form disclosing ownership of 5,406,193 shares of CytomX Therapeutics, Inc. (US:CTMX) valued at $25,409,107 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 342,304 shares of CytomX Therapeutics, Inc.. This represents a change in shares of 1,479.35% during the quarter. The current value of the position is $16,218,579 USD.

Citadel Advisors Llc has a history of taking positions in derivatives of the underlying security (CTMX) in the form of stock options. The firm currently holds call options representing 136,600 of underlying shares valued at $642,020 USD and put options representing 356,400 of underlying shares valued at $1,675,080 USD .

Note: prior versions of this page mistakenly stated that the share values represented the number of options, not the number of underlying shares. For more information on the data backing these reports, please see the SEC document Frequently Asked Questions About Form 13F.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Institutional Put/Call Ratios
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In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

CTMX / CytomX Therapeutics, Inc. Historical Put/Call Ratio
Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date
Effective
Date
Form Security Class ID Avg Price
Paid (Est)
Reported
Shares
ΔShares ΔShares
(%)
Reported
Value
(x1000)
ΔValue
(%)
Alloc
(%)
ΔAlloc ΔAlloc (%) Cost Basis
(x1000)
Unrealized
Gain/Loss
(x1000)
2026-05-15 2026-03-31 13F CYTOMX THERAPEUTICS COM 23284F105 5,406,193 5,063,889 1,479.35 25,409 1,642.73 0.0036
2026-02-17 2025-12-31 13F CYTOMX THERAPEUTICS COM 23284F105 342,304 -1,458,131 -80.99 1,458 -74.61 0.0002
2025-11-14 2025-09-30 13F CYTOMX THERAPEUTICS COM 23284F105 1,800,435 1,714,926 2,005.55 5,743 2,860.31 0.0009
2025-08-14 2025-06-30 13F CYTOMX THERAPEUTICS COM 23284F105 85,509 85,409 85,409.00 194 0.0000
2025-05-15 2025-03-31 13F CYTOMX THERAPEUTICS COM 23284F105 100 -322,211 -99.97 0 -100.00 0.0000
2025-02-14 2024-12-31 13F CYTOMX THERAPEUTICS COM 23284F105 322,311 5,192 1.64 332 -11.50 0.0001
2024-11-14 2024-09-30 13F CYTOMX THERAPEUTICS COM 23284F105 317,119 -177,524 -35.89 374 -37.98 0.0001
2024-08-14 2024-06-30 13F CYTOMX THERAPEUTICS COM 23284F105 494,643 457,866 1,244.98 603 653.75 0.0001
2024-05-15 2024-03-31 13F CYTOMX THERAPEUTICS COM 23284F105 36,777 -216,506 -85.48 80 -79.59 0.0000
2024-02-14 2023-12-31 13F CYTOMX THERAPEUTICS COM 23284F105 253,283 193,117 320.97 393 409.09 0.0001
2023-11-14 2023-09-30 13F CYTOMX THERAPEUTICS COM 23284F105 60,166 51,312 579.53 78 413.33 0.0000
2023-08-14 2023-06-30 13F CYTOMX THERAPEUTICS COM 23284F105 8,854 -269,823 -96.82 15 -96.43 0.0000
2023-05-15 2023-03-31 13F CYTOMX THERAPEUTICS COM 23284F105 278,677 -179,241 -39.14 421 -42.62 0.0001
2023-02-14 2022-12-31 13F CYTOMX THERAPEUTICS COM 23284F105 457,918 408,759 831.50 733 930.99 0.0002
2022-11-14 2022-09-30 13F CYTOMX THERAPEUTICS COM 23284F105 49,159 -286,830 -85.37 71 -88.46 0.0000
2022-08-15 2022-06-30 13F CYTOMX THERAPEUTICS COM 23284F105 335,989 321,607 2,236.18 615 1,518.42 0.0002
2022-05-16 2022-03-31 13F CYTOMX THERAPEUTICS COM 23284F105 14,382 -23,688 -62.22 38 -76.97 0.0000
2022-02-14 2021-12-31 13F CYTOMX THERAPEUTICS COM 23284F105 38,070 38,070 165 0.0000
2022-03-11 2021-09-30 13F/A-1 CYTOMX THERAPEUTICS COM 23284F105 0 -769,766 -100.00 0 -100.00
2021-11-15 2021-09-30 13F CYTOMX THERAPEUTICS COM 23284F105 0 -769,766 0
2021-08-16 2021-06-30 13F CYTOMX THERAPEUTICS COM 23284F105 769,766 -160,144 -17.22 4,873 -32.21 0.0011
2021-05-21 2021-03-31 13F/A-1 CYTOMX THERAPEUTICS COM 23284F105 929,910 744,644 401.93 7,188 492.58 0.0018
2021-05-17 2021-03-31 13F CYTOMX THERAPEUTICS COM 23284F105 929,910 744,644 7,188 0.0018
2021-02-16 2020-12-31 13F CYTOMX THERAPEUTICS COM 23284F105 185,266 -95,660 -34.05 1,213 -35.06 0.0003
2020-11-16 2020-09-30 13F CYTOMX THERAPEUTICS COM 23284F105 280,926 212,861 312.73 1,868 229.45 0.0005
2020-08-14 2020-06-30 13F CYTOMX THERAPEUTICS Cmn 23284F105 68,065 -134,041 -66.32 567 -63.42 0.0002
2020-05-15 2020-03-31 13F CYTOMX THERAPEUTICS Cmn 23284F105 202,106 -233,463 -53.60 1,550 -57.17 0.0007
2020-02-14 2019-12-31 13F CYTOMX THERAPEUTICS Cmn 23284F105 435,569 203,094 87.36 3,619 110.90 0.0016
2019-11-14 2019-09-30 13F CYTOMX THERAPEUTICS Cmn 23284F105 232,475 232,475 -46.63 1,716 -52.58 0.0008
2019-08-14 2019-06-30 13F CYTOMX THERAPEUTICS Cmn 23284F105 0 -34,290 -100.00 0 -100.00
2019-05-15 2019-03-31 13F CYTOMX THERAPEUTICS Cmn 23284F105 34,290 34,290 368 0.0002
2019-02-14 2018-12-31 13F CYTOMX THERAPEUTICS Cmn 23284F105 0 -27,081 -100.00 0 -100.00
2018-11-13 2018-09-30 13F CYTOMX THERAPEUTICS Cmn 23284F105 27,081 4,602 20.47 501 -2.53 0.0002
2018-08-14 2018-06-30 13F/A-1 CYTOMX THERAPEUTICS Cmn 23284F105 22,479 -24,537 -52.19 514 -61.58 0.0003
2018-08-10 2018-06-30 13F CYTOMX THERAPEUTICS Cmn 23284F105 22,479 -24,537 514
2018-05-14 2018-03-31 13F/A-1 CYTOMX THERAPEUTICS Cmn 23284F105 47,016 47,016 109.16 1,338 160.31 0.0007
2018-05-11 2018-03-31 13F CYTOMX THERAPEUTICS Cmn 23284F105 47,016 47,016 1,338
2017-11-09 2017-09-30 13F CYTOMX THERAPEUTICS Cmn 23284F105 0 -31,043 -100.00 0 -100.00
2017-08-11 2017-06-30 13F CYTOMX THERAPEUTICS Cmn 23284F105 31,043 12,927 71.36 481 53.67 0.0004
2017-05-12 2017-03-31 13F CYTOMX THERAPEUTICS Cmn 23284F105 18,116 18,116 313 0.0003
Disclosed Call Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share
Price
Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-15 2026-03-31 13F CYTOMX THERAPEUTICS COM Call 136,600 72.26 642 90.50 n/a n/a n/a
2026-02-17 2025-12-31 13F CYTOMX THERAPEUTICS COM Call 79,300 -41.04 338 -21.45 n/a n/a n/a
2025-11-14 2025-09-30 13F CYTOMX THERAPEUTICS COM Call 134,500 -10.21 429 26.18 n/a n/a n/a
2025-08-14 2025-06-30 13F CYTOMX THERAPEUTICS COM Call 149,800 1,583.15 340 6,700.00 n/a n/a n/a
2025-05-15 2025-03-31 13F CYTOMX THERAPEUTICS COM Call 8,900 140.54 6 66.67 n/a n/a n/a
2025-02-14 2024-12-31 13F CYTOMX THERAPEUTICS COM Call 3,700 23.33 4 0.00 n/a n/a n/a
2024-11-14 2024-09-30 13F CYTOMX THERAPEUTICS COM Call 3,000 -45.45 4 -50.00 n/a n/a n/a
2024-08-14 2024-06-30 13F CYTOMX THERAPEUTICS COM Call 5,500 -38.20 7 -68.42 n/a n/a n/a
2024-05-15 2024-03-31 13F CYTOMX THERAPEUTICS COM Call 8,900 -54.36 19 -36.67 n/a n/a n/a
2024-02-14 2023-12-31 13F CYTOMX THERAPEUTICS COM Call 19,500 -43.48 30 -31.82 n/a n/a n/a
2023-11-14 2023-09-30 13F CYTOMX THERAPEUTICS COM Call 34,500 -1.71 45 -26.67 n/a n/a n/a
2023-08-14 2023-06-30 13F CYTOMX THERAPEUTICS COM Call 35,100 140.41 60 172.73 n/a n/a n/a
2023-05-15 2023-03-31 13F CYTOMX THERAPEUTICS COM Call 14,600 -17.98 22 -21.43 n/a n/a n/a
2023-02-14 2022-12-31 13F CYTOMX THERAPEUTICS COM Call 17,800 16.34 28 27.27 n/a n/a n/a
2022-11-14 2022-09-30 13F CYTOMX THERAPEUTICS COM Call 15,300 4.08 22 -18.52 n/a n/a n/a
2022-08-15 2022-06-30 13F CYTOMX THERAPEUTICS COM Call 14,700 -11.45 27 -38.64 n/a n/a n/a
2022-05-16 2022-03-31 13F CYTOMX THERAPEUTICS COM Call 16,600 -52.97 44 -71.24 n/a n/a n/a
2022-02-14 2021-12-31 13F CYTOMX THERAPEUTICS COM Call 35,300 153 n/a n/a n/a
2021-08-16 2021-06-30 13F CYTOMX THERAPEUTICS COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2021-05-21 2021-03-31 13F/A CYTOMX THERAPEUTICS COM Call 16,300 126 n/a n/a n/a
2021-05-17 2021-03-31 13F CYTOMX THERAPEUTICS COM Call 16,300 126 n/a n/a n/a
Disclosed Put Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share Price Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-15 2026-03-31 13F CYTOMX THERAPEUTICS COM Put 356,400 596.09 1,675 668.35 n/a n/a n/a
2026-02-17 2025-12-31 13F CYTOMX THERAPEUTICS COM Put 51,200 17.70 218 57.97 n/a n/a n/a
2025-11-14 2025-09-30 13F CYTOMX THERAPEUTICS COM Put 43,500 -58.96 139 -42.50 n/a n/a n/a
2025-08-14 2025-06-30 13F CYTOMX THERAPEUTICS COM Put 106,000 121.29 241 700.00 n/a n/a n/a
2025-05-15 2025-03-31 13F CYTOMX THERAPEUTICS COM Put 47,900 919.15 30 650.00 n/a n/a n/a
2025-02-14 2024-12-31 13F CYTOMX THERAPEUTICS COM Put 4,700 -43.37 5 -55.56 n/a n/a n/a
2024-11-14 2024-09-30 13F CYTOMX THERAPEUTICS COM Put 8,300 9.21 10 0.00 n/a n/a n/a
2024-08-14 2024-06-30 13F CYTOMX THERAPEUTICS COM Put 7,600 68.89 9 0.00 n/a n/a n/a
2024-05-15 2024-03-31 13F CYTOMX THERAPEUTICS COM Put 4,500 40.62 10 125.00 n/a n/a n/a
2024-02-14 2023-12-31 13F CYTOMX THERAPEUTICS COM Put 3,200 -5.88 5 0.00 n/a n/a n/a
2023-11-14 2023-09-30 13F CYTOMX THERAPEUTICS COM Put 3,400 -67.92 4 -77.78 n/a n/a n/a
2023-08-14 2023-06-30 13F CYTOMX THERAPEUTICS COM Put 10,600 39.47 18 63.64 n/a n/a n/a
2023-05-15 2023-03-31 13F CYTOMX THERAPEUTICS COM Put 7,600 65.22 11 57.14 n/a n/a n/a
2023-02-14 2022-12-31 13F CYTOMX THERAPEUTICS COM Put 4,600 7 n/a n/a n/a
2022-08-15 2022-06-30 13F CYTOMX THERAPEUTICS COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2022-05-16 2022-03-31 13F CYTOMX THERAPEUTICS COM Put 11,400 -73.30 30 -83.78 n/a n/a n/a
2022-02-14 2021-12-31 13F CYTOMX THERAPEUTICS COM Put 42,700 314.56 185 255.77 n/a n/a n/a
2021-11-15 2021-09-30 13F CYTOMX THERAPEUTICS Cmn Put 10,300 -45.21 52 -56.30 n/a n/a n/a
2021-08-16 2021-06-30 13F CYTOMX THERAPEUTICS COM Put 18,800 -23.58 119 -37.37 n/a n/a n/a
2021-05-21 2021-03-31 13F/A CYTOMX THERAPEUTICS COM Put 24,600 190 n/a n/a n/a
2021-05-17 2021-03-31 13F CYTOMX THERAPEUTICS COM Put 24,600 190 n/a n/a n/a
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.