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* Kruse Bo (Last) (First) (Middle) C/O Y-MABS THERAPEUTICS, INC. 230 PARK AVE, 33RD FLOOR (Street) NEW YORK NY 10169 (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 10% Owner X Officer (give title below) Other (specify below) EVP, CFO, Secy & Treas.	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	300,000	D
Common Stock	57,077	I	By Investeringsselskabet G.H. ApS(1)

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
Employee Stock Option (right to buy)	(2)	06/10/2025	Common Stock	300,000	2	D
Employee Stock Option (right to buy)	(3)	10/21/2026	Common Stock	133,000	4.38	D
Employee Stock Option (right to buy)	(4)	12/14/2026	Common Stock	14,000	8.5	D
Employee Stock Option (right to buy)	(5)	04/24/2028	Common Stock	75,000	11.16	D

Explanation of Responses:

1. Investeringsselskabet G.H. ApS is Reporting Person's personal holding company of which Reporting Person is the sole owner and as such has the sole voting and dispositive power with respect to such shares.

2. The stock option vested and became exercisable as to 25% of the shares subject to the option on June 10, 2016, and thereafter vests as to 1/48th of the shares in equal monthly installments, until such time as the option is 100% vested, subject to the continuing employment of the Reporting Person on each vesting date.

3. The stock option vested and became exercisable as to 25% of the shares subject to the option on October 21, 2017, and thereafter vests as to 1/48th of the shares in equal monthly installments, until such time as the option is 100% vested, subject to the continuing employment of the Reporting Person on each vesting date.

4. The stock option vested and became exercisable as to 25% of the shares subject to the option on December 14, 2017, and thereafter vests as to 1/48th of the shares in equal monthly installments, until such time as the option is 100% vested, subject to the continuing employment of the Reporting Person on each vesting date.

5. The stock option shall vest and become exercisable as to 25% of the shares subject to the option on April 24, 2019, and thereafter vests as to 1/48th of the shares in equal monthly installments, until such time as the option is 100% vested, subject to the continuing employment of the Reporting Person on each vesting date.

	/s/ Bo Kruse	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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