Perceptive affiliates report 10.1M shares (4.6%) in CytomX

CytomX Therapeutics reports that Perceptive Advisors, Joseph Edelman and Perceptive Life Sciences Master Fund each beneficially own 10,098,824 shares of common stock, representing 4.6% of the class.

Rhea-AI Filing Summary

CytomX Therapeutics reports that Perceptive Advisors, Joseph Edelman and Perceptive Life Sciences Master Fund each beneficially own 10,098,824 shares of common stock, representing 4.6% of the class. The filing states there were 217,702,919 outstanding shares as of April 30, 2026.

The report attributes the holdings to the Master Fund (direct holder) and notes that Perceptive Advisors serves as investment manager and Mr. Edelman is managing member; all three disclose shared voting and dispositive power over the 10,098,824 shares.

Insights

Institutional Ownership Analyst

Perceptive-affiliated entities report a 4.6% stake in CytomX.

The filing shows the Master Fund directly holds 10,098,824 shares, with Perceptive Advisors and Joseph Edelman reported as having shared voting and dispositive power. The ownership percentage is calculated using April 30, 2026 outstanding shares.

Cash‑flow treatment and planned transactions are not disclosed; subsequent filings would be needed to show any sales, purchases, or changes in voting arrangements.

Corporate Governance Specialist

Shared control signals manager-level influence, not sole control.

The report lists shared voting power and shared dispositive power for 10,098,824 shares, indicating coordinated authority among the Master Fund, Perceptive Advisors, and Mr. Edelman. This is a typical disclosure structure for funds where an adviser exercises influence.

Watch for future amendments or Form 13D/Form 4 filings if the group increases stake above filing thresholds or alters voting arrangements.

Key Figures

Shares beneficially owned: 10,098,824 shares Percent of class: 4.6% Shares outstanding: 217,702,919 shares +1 more

4 metrics

Shares beneficially owned 10,098,824 shares Directly held by Perceptive Life Sciences Master Fund

Percent of class 4.6% Reported for Perceptive Advisors, Mr. Edelman, and the Master Fund

Shares outstanding 217,702,919 shares Outstanding shares as of April 30, 2026

Shared voting power 10,098,824 shares Shared voting power reported by each Reporting Person

Key Terms

Schedule 13G/A, beneficially own, shared dispositive power, CUSIP

4 terms

Schedule 13G/A regulatory

"Amendment No. 1 to Schedule 13G/A reporting beneficial ownership"

A Schedule 13G/A is an amended public filing with the U.S. securities regulator that updates a previous Schedule 13G, disclosing when an individual or group holds a substantial (typically over 5%) stake in a company and is claiming a passive, non‑controlling intent. Investors monitor these updates because rising or falling holdings can signal changing confidence, potential future moves, or shifts in voting power — like watching a public ledger where large shareholders quietly adjust their positions.

beneficially own financial

"The Master Fund directly holds 10,098,824 shares of Common Stock"

Beneficially own means having the economic rights and risks of a security—such as the right to receive dividends, sell the shares, or profit from price changes—whether or not your name appears on the official share register. Think of it like renting a car: you use it and reap the benefits even if the title lists someone else. Investors care because beneficial ownership determines who truly controls value, must be disclosed under securities rules, and can signal potential influence or trading activity that affects a stock’s price.

shared dispositive power governance

"Shared dispositive power 10,098,824.00 reported for each Reporting Person"

CUSIP technical

"CUSIP No.: 23284F105"

A CUSIP is a nine-character alphanumeric code that uniquely identifies a U.S. or Canadian financial security—such as a stock, bond, or fund share—like a Social Security number for an investment. It matters to investors because brokers, exchanges and record-keepers use the CUSIP to match trades, track ownership, settle transactions and pull accurate records, reducing errors and ensuring money and securities go to the right place.

FAQ

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

What stake does Perceptive Advisors report in CytomX (CTMX)?

Perceptive-affiliated parties report a 4.6% stake, or 10,098,824 shares. The filing says the percentage is based on 217,702,919 outstanding shares as of April 30, 2026, and shows shared voting and dispositive power among the reporting entities.

Who directly holds the 10,098,824 CytomX shares reported?

The Perceptive Life Sciences Master Fund directly holds the 10,098,824 shares. Perceptive Advisors is the investment manager and Joseph Edelman is the managing member; both are reported as having shared voting and dispositive power over those shares.

How was the 4.6% ownership percentage calculated for CTMX?

The 4.6% is based on 217,702,919 shares outstanding as of April 30, 2026. The filing cites the issuer's Form 10-Q filed May 7, 2026, as the source for the outstanding share count used in the percentage calculation.

Does the filing show sole voting or disposal power for the reporting persons?

No; the filing reports zero sole voting and zero sole dispositive power. Instead it lists shared voting power and shared dispositive power for 10,098,824 shares, indicating coordinated authority rather than unilateral control.

Will this Schedule 13G/A trigger a change to CTMX governance rights?

The filing does not itself change governance rights. It discloses ownership and shared powers; any governance impact would depend on future actions, votes, or additional share accumulation disclosed in later filings.

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

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Accepted by SEC EDGAR 05/15/2026 - 04:00 PM EDT Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

CytomX Therapeutics, Inc.

(Name of Issuer)

Common Stock, $0.00001 par value per share

(Title of Class of Securities)

23284F105

(CUSIP Number)

03/31/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 23284F105

1

Names of Reporting Persons

Perceptive Advisors LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 10,098,824.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 10,098,824.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

10,098,824.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

4.6 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

CUSIP Number(s): 23284F105

1

Names of Reporting Persons

Joseph Edelman

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 10,098,824.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 10,098,824.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

10,098,824.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

4.6 %

12

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13G

CUSIP Number(s): 23284F105

1

Names of Reporting Persons

Perceptive Life Sciences Master Fund, Ltd.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 10,098,824.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 10,098,824.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

10,098,824.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

4.6 %

12

Type of Reporting Person (See Instructions)

CO

SCHEDULE 13G

Item 1.
(a)	Name of issuer: CytomX Therapeutics, Inc.
(b)	Address of issuer's principal executive offices: 151 Oyster Point Blvd., Suite 400, South San Francisco, CA 94080
Item 2.
(a)	Name of person filing: The names of the persons filing this report (collectively, the "Reporting Persons") with respect to shares of Common Stock, par value $0.00001 per share (the "Common Stock") of CytomX Therapeutics, Inc. (the "Issuer") are: Perceptive Advisors LLC ("Perceptive Advisors") Joseph Edelman ("Mr. Edelman") Perceptive Life Sciences Master Fund, Ltd. (the "Master Fund")
(b)	Address or principal business office or, if none, residence: The address of the principal business office of each of the Reporting Persons is: 51 Astor Place, 10th Floor New York, NY 10003
(c)	Citizenship: Perceptive Advisors is a Delaware limited liability company Mr. Edelman is a United States citizen The Master Fund is a Cayman Islands corporation
(d)	Title of class of securities: Common Stock, $0.00001 par value per share
(e)	CUSIP No.: 23284F105
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: The information required by this item with respect to each Reporting Person is set forth in Rows 5 through 9 and 11 of the cover pages to this Schedule 13G. The ownership percentages reported are based on 217,702,919 outstanding shares of Common Stock as of April 30, 2026, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on May 7, 2026. The Master Fund directly holds 10,098,824 shares of Common Stock. Perceptive Advisors serves as the investment manager to the Master Fund and may be deemed to beneficially own the securities directly held by the Master Fund. Mr. Edelman is the managing member of Perceptive Advisors and may be deemed to beneficially own the securities directly held by the Master Fund.
(b)	Percent of class: Perceptive Advisors: 4.6% Mr. Edelman: 4.6% Master Fund: 4.6%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: Perceptive Advisors: 0 Mr. Edelman: 0 Master Fund: 0
	(ii) Shared power to vote or to direct the vote: Perceptive Advisors: 10,098,824 Mr. Edelman: 10,098,824 Master Fund: 10,098,824
	(iii) Sole power to dispose or to direct the disposition of: Perceptive Advisors: 0 Mr. Edelman: 0 Master Fund: 0
	(iv) Shared power to dispose or to direct the disposition of: Perceptive Advisors: 10,098,824 Mr. Edelman: 10,098,824 Master Fund: 10,098,824
Item 5.	Ownership of 5 Percent or Less of a Class.
	Ownership of 5 percent or less of a class
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Perceptive Advisors LLC

Signature:	/s/ Joseph Edelman
Name/Title:	Joseph Edelman, Managing Member
Date:	05/15/2026

Joseph Edelman

Signature:	/s/ Joseph Edelman
Name/Title:	Joseph Edelman
Date:	05/15/2026

Perceptive Life Sciences Master Fund, Ltd.

Signature:	/s/ Joseph Edelman
Name/Title:	Joseph Edelman, Managing Member
Date:	05/15/2026