[Form 4] CytomX Therapeutics, Inc. Insider Trading Activity

Rhea-AI Filing Summary

CytomX Therapeutics (CTMX) reported an insider transaction by its CEO and Director, Sean A. McCarthy. On 11/06/2025, he sold 101,793 shares of Class A common stock pursuant to a Rule 10b5-1 trading plan adopted on August 27, 2024.

The sale was executed at a weighted average price of $4.5377, with trades occurring between $4.50 and $4.62. Following this transaction, he beneficially owns 987,891 shares directly, which include 488,750 restricted stock units. He also holds 93,158 shares indirectly through the Sean A. McCarthy 2018 Trust, where he is trustee.

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.

151 OYSTER POINT BLVD., STE. 400

(Street)

SOUTH SAN FRANCISCO CA 94080

(City) (State) (Zip)

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

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

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

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

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

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
Class A Common Stock	11/06/2025		S(1)		101,793	D	$4.5377(2)	987,891(3)	D
Class A Common Stock								93,158	I	See footnote(4)

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

Explanation of Responses:

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

2. 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.

3. Includes 488,750 restricted stock units.

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

	/s/ Christopher Ogden, as Attorney-in-Fact for Sean A. McCarthy	11/10/2025
	** 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.

FAQ

What insider transaction did CTMX disclose?

On 11/06/2025, CEO/Director Sean A. McCarthy sold 101,793 shares of Class A common stock.

At what price were the CTMX shares sold?

The weighted average sale price was $4.5377, with trades between $4.50 and $4.62.

Was the sale under a Rule 10b5-1 plan?

Yes. The trades were made under a Rule 10b5-1 trading plan adopted on August 27, 2024.

How many CTMX shares does the CEO hold after the sale?

He beneficially owns 987,891 shares directly, including 488,750 RSUs.

Does the CEO have any indirect holdings?

Yes. He indirectly holds 93,158 shares via the Sean A. McCarthy 2018 Trust, where he is trustee.

Who signed the filing on behalf of the reporting person?

It was signed by /s/ Christopher Ogden as Attorney-in-Fact for Sean A. McCarthy on 11/10/2025.