Statement of Changes in Beneficial Ownership (4)

FORM 4

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

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

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

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3235-0287

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

1. Name and Address of Reporting Person * Moller-San Pedro Claus Juan	2. Issuer Name and Ticker or Trading Symbol Y-mAbs Therapeutics, Inc. [ YMAB ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director                    _____ 10% Owner __X__ Officer (give title below)    _____ Other (specify below) Chief Executive Officer
(Last)          (First)          (Middle) C/O Y-MABS THERAPEUTICS, INC., 230 PARK AVENUE, SUITE 3350	3. Date of Earliest Transaction (MM/DD/YYYY) 5/13/2020
(Street) NEW YORK, NY 10169 (City)        (State)        (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	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. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. 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								15625	D
Common Stock								1900	I	By minor child (1)(2)
Common Stock	5/13/2020		S		60846	D	$37.7531 (3)	796457	I	By CM Holding 2015 ApS (4)
Common Stock	5/14/2020		S		139154	D	$36.0248 (5)	657303	I	By CM Holding 2015 ApS (4)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. 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		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 of Derivative Security: 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)	Reporting Person may be deemed to have a pecuniary interest in the securities due to family relationship.
(2)	Reporting Person disclaims beneficial ownership of the securities reported and this report shall not be deemed an admission that Reporting Person is the beneficial owner of such securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.
(3)	This transaction was executed in multiple trades at prices ranging from $39.13 to $37.50. The price reported reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer or a security holder of the Issuer full information regarding the number of shares and prices at which the transaction was effected.
(4)	CM Holding 2015 ApS is Reporting Person's personal holding company of which Reporting Person is the sole owner and as such Reporting Person has sole voting and dispositive power with respect to such shares.
(5)	This transaction was executed in multiple trades at prices ranging from $36.34 to $36.02. The price reported reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer or a security holder of the Issuer full information regarding the number of shares and prices at which the transaction was effected.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Moller-San Pedro Claus Juan C/O Y-MABS THERAPEUTICS, INC. 230 PARK AVENUE, SUITE 3350 NEW YORK, NY 10169	X		Chief Executive Officer

Signatures
/s/ Claus Juan Moller San Pedro		5/15/2020
**Signature of Reporting Person		Date