Y-mAbs merger closes; insider holdings cashed out at $8.60 per share

Rhea-AI Filing Summary

Y-mAbs Therapeutics completed a merger on September 16, 2025 that resulted in all outstanding common shares and equity awards being cashed out. Under the Merger Agreement, each share was exchanged for $8.60 in cash and the company became an indirect wholly owned subsidiary of Perseus BidCo US, Inc. and its ultimate parent. The reporting person, Thomas Gad, disposed of or had converted into cash his directly and indirectly held common stock, restricted stock units, performance RSUs and stock options; following the transactions the report shows zero shares beneficially owned. Options with exercise prices equal to or above $8.60 were cancelled for no consideration, while other vested and unvested awards were converted into cash per the agreement.

Positive

• Merger completed with each share exchanged for $8.60 cash per share.
• All outstanding equity awards were settled in cash, providing immediate liquidity to holders.
• Issuer became an indirect wholly owned subsidiary of Perseus BidCo US and Ultimate Parent, completing the take-private.

Negative

• Reporting person’s beneficial ownership reduced to zero following the merger.
• Options with exercise prices equal to or above $8.60 were cancelled for no consideration, eliminating upside for those option holders.

Insights

M&A Specialist

TL;DR: The company was acquired for $8.60 per share and equity awards were cashed out, effecting a take-private transaction.

The Form 4 documents the mechanical outcomes for an insider following a tender offer and merger: shares, RSUs, PRSUs and options were either cashed out or cancelled per the Merger Agreement. The $8.60 per-share cash consideration is the controlling metric and drove the settlement values for awards. From a transaction-structure perspective, conversion of options and RSUs into cash simplifies post-close cap table management for the acquirer but eliminates residual upside for former holders. This is a routine equity settlement in a change-of-control where the purchaser gains full control.

Corporate Governance Expert

TL;DR: Insider disclosures show full disposition/settlement of holdings and typical governance treatment of awards at closing.

The Form 4 provides clear disclosure of the reporting person's direct and indirect holdings and confirms governance mechanics: the issuer continued as the surviving corporation and became an indirect wholly owned subsidiary, and awards were handled in accordance with the Merger Agreement. The filing notes that options with exercise prices at or above the merger price were cancelled without consideration, which is material to option holders. The signature by attorney-in-fact indicates the filing was executed on the insider's behalf.

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

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X

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

1. Name and Address of Reporting Person^*

Gad Thomas

(Last) (First) (Middle)

C/O Y-MABS THERAPEUTICS, INC.

202 CARNEGIE CENTER, SUITE 301

(Street)

PRINCETON NJ 08540

(City) (State) (Zip)

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 BUSINESS OFFICER

3. Date of Earliest Transaction (Month/Day/Year)
09/16/2025

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
Common Stock	09/16/2025(1)		U		245,486	D	$8.6(2)	0	D
Common Stock	09/16/2025(1)		D		60,235(3)	D	(4)	0	D
Common Stock	09/16/2025(1)		U		67,681	D	$8.6(2)	0	I	By GAD Enterprises LLC(5)
Common Stock	09/16/2025(1)		U		60,000	D	$8.6(2)	0	I	By Children(6)

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
Employee Stock Option (right to buy)	$4.38	09/16/2025(1)		D			143,169	(7)	10/21/2026	Common Stock	143,169	(7)	0	D
Employee Stock Option (right to buy)	$8.5	09/16/2025(1)		D			16,000	(7)	12/14/2026	Common Stock	16,000	(7)	0	D
Employee Stock Option (right to buy)	$11.16	09/16/2025(1)		D			100,000	(7)	04/24/2028	Common Stock	100,000	(7)	0	D
Employee Stock Option (right to buy)	$21.97	09/16/2025(1)		D			107,500	(7)	12/11/2028	Common Stock	107,500	(7)	0	D
Employee Stock Option (right to buy)	$30.34	09/16/2025(1)		D			130,000	(7)	01/07/2030	Common Stock	130,000	(7)	0	D
Employee Stock Option (right to buy)	$53.88	09/16/2025(1)		D			91,450	(7)	12/15/2030	Common Stock	91,450	(7)	0	D
Employee Stock Option (right to buy)	$15.73	09/16/2025(1)		D			110,000	(7)	12/14/2031	Common Stock	110,000	(7)	0	D
Employee Stock Option (right to buy)	$9.52	09/16/2025(1)		D			60,000	(7)	05/18/2032	Common Stock	60,000	(7)	0	D
Employee Stock Option (right to buy)	$4.7	09/16/2025(1)		D			242,200	(7)	01/17/2033	Common Stock	242,200	(7)	0	D
Employee Stock Option (right to buy)	$5.75	09/16/2025(1)		D			75,000	(7)	11/06/2033	Common Stock	75,000	(7)	0	D
Employee Stock Option (right to buy)	$9.83	09/16/2025(1)		D			132,500	(7)	01/18/2034	Common Stock	132,500	(7)	0	D
Employee Stock Option (right to buy)	$6.16	09/16/2025(1)		D			64,000	(7)	01/17/2035	Common Stock	64,000	(7)	0	D
Restricted Stock Units(8)	(9)	09/16/2025(1)		D			16,000	(9)	(9)	Common Stock	16,000	(9)	0	D
Restricted Stock Units(8)	(9)	09/16/2025(1)		D			16,000	(9)	(9)	Common Stock	16,000	(9)	0	D

Explanation of Responses:

1. Pursuant to the Agreement and Plan of Merger (the "Merger Agreement"), dated as of August 4, 2025, by and among Y-mAbs Therapeutics, Inc. (the "Issuer"), Yosemite Merger Sub, Inc. ("Purchaser"), Perseus BidCo US, Inc., a Delaware corporation ("Parent"), and Stark International Lux, a Luxembourg private limited liability company ("Ultimate Parent"), on September 16, 2025, Purchaser completed a tender offer for shares of common stock of the Issuer (each, a "Share") and thereafter merged with and into the Issuer, with the Issuer continuing as the surviving corporation and an indirect wholly owned subsidiary of Parent (the "Merger").

2. Pursuant to the terms of the Merger Agreement, the Shares were tendered at the Offer Acceptance Time (as defined in the Merger Agreement) in exchange for the right to receive $8.60 per Share, in cash, without interest, subject to any applicable withholding of taxes (the "Merger Consideration"). At the effective time of the Merger (being such date and at such time as the certificate of merger in respect of the Merger was duly filed with the Secretary of State of the State of Delaware in accordance with the DGCL) (the "Effective Time"), each issued and outstanding Share was cancelled in exchange for the Merger Consideration.

3. Represents restricted stock units ("RSUs") granted to the Reporting Person pursuant to the Issuer's 2018 Equity Incentive Plan. Each RSU represents a contingent right to receive one share of Common Stock on the vesting dates of the RSU.

4. At the Effective Time, pursuant to the Merger Agreement, each RSU award outstanding as of immediately prior to the Effective Time, whether vested or unvested, was cancelled and converted into the right to receive an amount in cash, without interest, equal to the product of (a) the total number of Shares issuable in settlement of such RSU award immediately prior to the Effective Time, multiplied by (b) the Merger Consideration.

5. Reporting Person is sole member of GAD Enterprises, LLC and the sole member and manager of GAD Management, LLC, the manager of GAD Enterprises, LLC, and as such Reporting Person has sole voting and dispositive power with respect to such shares.

6. Represents shares owned by Reporting Person's children who are deemed to share Reporting Person's household.

7. At the Effective Time, pursuant to the Merger Agreement, each stock option ("Option") outstanding as of immediately prior to the Effective Time, whether vested or unvested, was cancelled and converted into the right to receive cash, without interest, equal to the product of (a) the total number of Shares subject to such Option immediately prior to the Effective Time, multiplied by (b) the excess of the Merger Consideration over the exercise price payable per Share under such Option. Any Options with an exercise price equal to or in excess of the Merger Consideration were cancelled for no consideration.

8. Performance-Based RSUs ("PRSUs") granted to the Reporting Person pursuant to the 2018 Equity Incentive Plan of Y-mAbs Therapeutics, Inc. Each PRSU represents a contingent right to receive one share of Common Stock on the vesting dates of the PRSU.

9. At the Effective Time, pursuant to the Merger Agreement, each PRSU award outstanding as of immediately prior to the Effective Time, whether vested or unvested, was cancelled and converted into the right to receive an amount in cash, without interest, equal to the product of (a) the maximum number of Shares issuable in settlement of such PRSU award immediately prior to the Effective Time, multiplied by (b) the Merger Consideration.

Remarks:

The foregoing descriptions in the footnotes to this Form 4 are qualified in their entirety by reference to the terms of the Merger Agreement. In the event of any conflict between the descriptions above and the terms set forth in the Merger Agreement, the terms set forth in the Merger Agreement shall control.

	/s/ John LaRocca, Attorney-in-Fact	09/18/2025
	** 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).
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FAQ

What was the per-share merger consideration in the YMAB transaction?

The Merger Consideration was $8.60 per common share, paid in cash without interest.

What happened to Thomas Gad’s YMAB shares and equity awards?

All reported common shares, RSUs, PRSUs and stock options were either disposed of or converted into cash per the Merger Agreement, leaving zero shares beneficially owned.

Did any options get cancelled without payment in the YMAB merger?

Yes. The filing states that any options with an exercise price equal to or in excess of the Merger Consideration were cancelled for no consideration.

When was the effective date of the merger reported on this Form 4?

The Form 4 states the tender offer and merger were completed on September 16, 2025.

Who filed the Form 4 on behalf of the reporting person?

The Form 4 is signed by John LaRocca, Attorney-in-Fact for the reporting person on 09/18/2025.