SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person* Wedell-Wedellsborg Johan (Last) (First) (Middle) C/O WECO GROUP A/S RUNGSTED STRANDVEJ 113 (Street) RUNGSTED KYST G7 2960 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 09/20/2018	3. Issuer Name and Ticker or Trading Symbol Y-mAbs Therapeutics, Inc. [ YMAB ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director X 10% Owner Officer (give title below) Other (specify below)	5. 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 Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	1,683,496	I	By Weco Group A/S(1)
Common Stock	5,010,000	I	By WG Biotech ApS(2)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Non-Employee Stock Option (right to buy)	(3)	10/21/2026	Common Stock	36,000	4.38	D
Non-Employee Stock Option (right to buy)	(4)	04/24/2028	Common Stock	32,000	11.16	D

Explanation of Responses:

1. Reporting Person is the majority owner of Weco Group A/S and as such has sole voting and dispositive power with respect to such shares.

2. Reporting Person is the majority owner of WG Biotech ApS and as such has sole voting and dispositive power with respect to such shares.

3. The stock option vested and became exercisable as to 33% of the shares subject to the option on October 21, 2016, and thereafter vests as to 1/36th of the shares in equal monthly installments, until such time as the option is 100% vested, subject to the Reporting Person being a service provider on each vesting date.

4. 1/36th of the shares of the option to vest in equal monthly installments starting April 24, 2018 until such time as the option is 100% vested, subject to the Reporting Person continuing to be a service provider on each vesting date.

	/s/ Johan Wedell-Wedellsborg	09/20/2018
	** 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 5 (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).
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