Form 4: YMAB Director's Shares, RSUs and Options Converted to $8.60 Cash

Rhea-AI Filing Summary

Y-mAbs Therapeutics insider report shows completion of a merger and cash-out of equity awards. On 09/16/2025 the reporting person, Director Ashu Tyagi, had 5,825 shares tendered for $8.60 per share and 25,080 restricted stock units cancelled for cash under the Merger Agreement. Outstanding stock options were cancelled and converted into cash based on the excess of the $8.60 merger consideration over each option's exercise price; options with exercise prices at or above $8.60 were cancelled for no consideration. Following the transactions the reporting person reports 0 shares beneficially owned.

Positive

• Completed merger through tender offer and merger, delivering immediate liquidity to holders
• $8.60 per share cash consideration paid to tendering shareholders
• RSUs and in-the-money options converted to cash under defined Merger Agreement terms

Negative

• Reporting person reports 0 shares beneficially owned following the merger
• Options with exercise prices ≥ $8.60 were cancelled for no consideration, which may be a loss for some option holders

Insights

Financial Analyst

TL;DR: Merger completed; insiders cashed out at $8.60 per share, eliminating public float and converting equity awards to cash.

The Form 4 documents a completed transaction tied to a definitive Merger Agreement: a tender offer followed by a merger making the issuer an indirect wholly owned subsidiary. The cash consideration of $8.60 per share was paid at the offer acceptance time. Reported non-derivative and derivative holdings (shares, RSUs, and options) were either tendered or converted to cash, resulting in zero reported beneficial ownership post-closing for the reporting person. This is a material corporate control event with direct liquidity for insiders and elimination of public holder voting rights.

Corporate Governance Expert

TL;DR: Transaction is a control-changing merger; equity awards were cashed out per agreement, with some options potentially worthless.

The filing clarifies that all RSUs and outstanding options were cancelled and converted into cash per the Merger Agreement formula. Importantly, any option with an exercise price >= $8.60 was cancelled for no consideration, which can leave certain option holders uncompensated. The report shows the director's holdings were fully extinguished, consistent with a complete take-private acquisition and resulting governance transfer to the acquiror.

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

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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^*

TYAGI ASHU

(Last) (First) (Middle)

C/O Y-MABS THERAPEUTICS, INC.

230 PARK AVENUE, SUITE 3350

(Street)

NEW YORK NY 10169

(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
	Officer (give title below)		Other (specify below)

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		5,825	D	$8.6(2)	0	D
Common Stock	09/16/2025(1)		D		25,080(3)	D	(4)	0	D

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)	$21.45	09/16/2025(1)		D			16,000	(5)	06/12/2029	Common Stock	16,000	(5)	0	D
Employee Stock Option (right to buy)	$48.67	09/16/2025(1)		D			32,000	(5)	06/23/2030	Common Stock	32,000	(5)	0	D
Employee Stock Option (right to buy)	$48.67	09/16/2025(1)		D			11,000	(5)	06/23/2030	Common Stock	11,000	(5)	0	D
Employee Stock Option (right to buy)	$37.53	09/16/2025(1)		D			11,000	(5)	06/10/2031	Common Stock	11,000	(5)	0	D
Employee Stock Option (right to buy)	$16.64	09/16/2025(1)		D			16,000	(5)	07/15/2032	Common Stock	16,000	(5)	0	D
Employee Stock Option (right to buy)	$8.13	09/16/2025(1)		D			13,950	(5)	06/08/2033	Common Stock	13,950	(5)	0	D
Employee Stock Option (right to buy)	$12.01	09/16/2025(1)		D			14,545	(5)	06/11/2034	Common Stock	14,545	(5)	0	D
Employee Stock Option (right to buy)	$4.51	09/16/2025(1)		D			33,450	(5)	06/30/2035	Common Stock	33,450	(5)	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. 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.

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
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FAQ

What happened to Y-mAbs (YMAB) shares held by insiders?

Insiders tendered shares in a merger and received $8.60 per share in cash; the filing reports the reporting person holds 0 shares after the transaction.

How were RSUs and stock options treated in the merger?

All RSUs and options outstanding were cancelled and converted into cash per the Merger Agreement; cash paid equals the number of shares times $8.60, and options were paid only for the excess of $8.60 over the exercise price.

Did any equity awards become worthless?

Yes. The filing states any option with an exercise price equal to or above $8.60 was cancelled for no consideration.

When did the merger and related transactions occur?

The tender offer completion and merger occurred on 09/16/2025 as reported in this Form 4.

How much cash did the reporting person receive for tendered shares?

The Form 4 shows 5,825 shares tendered at $8.60 per share; additional RSUs were converted to cash at the same per-share amount.