CytomX corrects CEO holdings by 101,793 shares

Two later direct-holdings reports for the CEO are to be read as 101,793 shares higher, though neither is being amended.

This filing corrects an earlier one, and you can read the original Form 4 if you want to see what changed.

Rhea-AI Filing Summary

CytomX Therapeutics, Inc. CEO Sean A. McCarthy exercised 101,793 fully vested stock options at a $1.59 exercise price on November 6, 2025, acquiring 101,793 common shares and selling all 101,793 the same day at a weighted average $4.5377 per share. The sale was made under a Rule 10b5-1 trading plan adopted on August 27, 2024; sale prices ranged from $4.50 to $4.62.

After the exercise, 348,207 options were reported as held directly. Sean A. McCarthy 2018 Trust, of which he is trustee, held 93,158 common shares. The amendment corrects an omitted exercise in the earlier report and says direct holdings in later reports dated February 4 and March 19, 2026 should each be read as 101,793 shares higher; those reports are not amended.

Insider Trade Summary 10b5-1

Exercise and Sale: 101,793 shares ($300K approx. pre-tax spread)

Exercise and Sale 4 txns

Insider McCarthy Sean A.

Role CEO

Sold 101,793 shs ($462K)

Approx. gross sale proceeds $462K

Approx. exercise cost $162K

Approx. pre-tax spread $300K

Type	Security	Shares	Price	Value
Exercise	Stock Option (Right to Buy) F1, F6	101,793	$0.00	$0.00
Exercise	Common Stock F1, F4	101,793	$1.59	$162K
Sale	Common Stock F2, F3, F1, F4	101,793	$4.5377	$462K
holding	Common Stock F5	--	--	--

Holdings After Transaction: Stock Option (Right to Buy) — 348,207 contracts (Direct); Common Stock — 1,089,684 shares (Direct); Common Stock — 93,158 shares (Indirect, See footnote)

Footnotes (6)

1. F1. This Form 4/A restates in its entirety the original Form 4 filed on 11/10/2025 (the "Original Form 4") to report an inadvertently omitted exercise that was part of a same-day exercise-and-sale transaction; the sale was timely reported in the Original Form 4. Due to the omission, the Original Form 4 understated the Reporting Person's direct holdings following the reported transactions by 101,793 shares, and this understatement carried forward into Column 5 of Table I of the Reporting Person's Forms 4 filed on 2/4/2026 and 3/19/2026 (the "Subsequent Reports"). The direct holdings reported in Column 5 of Table I of this Form 4/A have been corrected. The Subsequent Reports are not being amended; the direct holdings amounts reported therein should each be read as increased by 101,793 shares.
2. F2. The transactions reported herein were effected pursuant to the Reporting Person's Rule 10b5-1 trading plan, adopted on August 27, 2024.
3. F3. This transaction was executed in multiple trades at prices ranging from $4.50 to $4.62, inclusive. The price reported above reflects the weighted average sale price. The Reporting Person undertakes to provide upon request by the staff of the Securities and Exchange Commission, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate sale price.
4. F4. Includes 488,750 restricted stock units.
5. F5. Shares held by Sean A. McCarthy 2018 Trust, of which the Reporting Person is trustee.
6. F6. This option is fully vested and exercisable.

Key Figures

Options exercised: 101,793 options Exercise price: $1.59 per share Weighted average sale price: $4.5377 per share +3 more

6 metrics

Options exercised 101,793 options November 6, 2025

Exercise price $1.59 per share Options exercised November 6, 2025

Weighted average sale price $4.5377 per share Sale of 101,793 common shares on November 6, 2025

Direct options following transaction 348,207 options Reported after the November 6, 2025 exercise

Trust-held common shares 93,158 shares Held by Sean A. McCarthy 2018 Trust, of which he is trustee

Direct-holdings correction 101,793 shares Increase to the direct holdings amounts in each of two later reports

Key Terms

Rule 10b5-1 trading plan, weighted average sale price, restricted stock units, fully vested and exercisable

4 terms

Rule 10b5-1 trading plan financial

"pursuant to the Reporting Person's Rule 10b5-1 trading plan"

A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.

weighted average sale price financial

"reflects the weighted average sale price"

restricted stock units financial

"Includes 488,750 restricted stock units"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

fully vested and exercisable financial

"This option is fully vested and exercisable"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many CTMX shares did CEO Sean A. McCarthy exercise and sell?

On November 6, 2025, he exercised 101,793 options at $1.59 per share and sold 101,793 common shares at a weighted average $4.5377 per share. The sale was made under a Rule 10b5-1 trading plan adopted on August 27, 2024; prices ranged from $4.50 to $4.62.

Why did CTMX's reported direct holdings change?

An inadvertently omitted option exercise understated direct holdings following the transactions by 101,793 shares. Direct holdings in Sean A. McCarthy's reports dated February 4 and March 19, 2026 should each be read as 101,793 shares higher; those reports are not being amended.

AI-generated analysis. How Rhea-AI works. Not financial advice.

Form 4 Insider Transactions: What Each Field Means →

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Available on EDGAR 10/16/2026 - 07:40 PM EDT Accepted by SEC EDGAR 10/16/2026 - 07:40 PM EDT Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

X

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

McCarthy Sean A.

(Last) (First) (Middle)

C/O CYTOMX THERAPEUTICS, INC.

5959 HORTON STREET, SUITE 300

(Street)

EMERYVILLE CALIFORNIA 94608

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
CytomX Therapeutics, Inc. [ CTMX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	CEO

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
11/06/2025

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)
11/10/2025

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	11/06/2025		M(1)		101,793	A	$1.59	1,191,477(4)	D
Common Stock	11/06/2025		S(2)		101,793	D	$4.5377(3)	1,089,684(1)(4)	D
Common Stock								93,158	I	See footnote(5)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Option (Right to Buy)	$1.59	11/06/2025		M(1)			101,793	(6)	08/09/2032	Common Stock	101,793	$0	348,207	D

Explanation of Responses:

1. This Form 4/A restates in its entirety the original Form 4 filed on 11/10/2025 (the "Original Form 4") to report an inadvertently omitted exercise that was part of a same-day exercise-and-sale transaction; the sale was timely reported in the Original Form 4. Due to the omission, the Original Form 4 understated the Reporting Person's direct holdings following the reported transactions by 101,793 shares, and this understatement carried forward into Column 5 of Table I of the Reporting Person's Forms 4 filed on 2/4/2026 and 3/19/2026 (the "Subsequent Reports"). The direct holdings reported in Column 5 of Table I of this Form 4/A have been corrected. The Subsequent Reports are not being amended; the direct holdings amounts reported therein should each be read as increased by 101,793 shares.

2. The transactions reported herein were effected pursuant to the Reporting Person's Rule 10b5-1 trading plan, adopted on August 27, 2024.

3. This transaction was executed in multiple trades at prices ranging from $4.50 to $4.62, inclusive. The price reported above reflects the weighted average sale price. The Reporting Person undertakes to provide upon request by the staff of the Securities and Exchange Commission, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate sale price.

4. Includes 488,750 restricted stock units.

5. Shares held by Sean A. McCarthy 2018 Trust, of which the Reporting Person is trustee.

6. This option is fully vested and exercisable.

	/s/ Christopher Ogden, as Attorney-in-Fact for Sean A. McCarthy	10/16/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)