David N. Gill - Sep 16, 2025 Form 4 Insider Report for Y-mAbs Therapeutics, Inc. (YMAB)

Role
Director
Signature
/s/ John LaRocca, Attorney-in-Fact
Stock symbol
YMAB
Transactions as of
Sep 16, 2025
Transactions value $
-$50,095
Form type
4
Date filed
9/18/2025, 09:27 PM
Previous filing
Jul 2, 2025
SEC
View on sec.gov

Reporting Owners (1)

Name Relationship Address Signature Signature date CIK
GILL DAVID N Director C/O Y-MABS THERAPEUTICS, INC., 230 PARK AVENUE, SUITE 3350, NEW YORK /s/ John LaRocca, Attorney-in-Fact 2025-09-18 0001106519

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
transaction YMAB Common Stock Disposed to Issuer -$50.1K -5.83K -100% $8.60 0 Sep 16, 2025 Direct F1, F2
transaction YMAB Common Stock Disposed to Issuer -25.1K -100% 0 Sep 16, 2025 Direct F1, F3, F4

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Underlying Class Amount Exercise Price Ownership Footnotes
transaction YMAB Employee Stock Option (right to buy) Disposed to Issuer -24K -100% 0 Sep 16, 2025 Common Stock 24K $11.16 Direct F1, F5
transaction YMAB Employee Stock Option (right to buy) Disposed to Issuer -16K -100% 0 Sep 16, 2025 Common Stock 16K $21.45 Direct F1, F5
transaction YMAB Employee Stock Option (right to buy) Disposed to Issuer -11K -100% 0 Sep 16, 2025 Common Stock 11K $48.67 Direct F1, F5
transaction YMAB Employee Stock Option (right to buy) Disposed to Issuer -11K -100% 0 Sep 16, 2025 Common Stock 11K $37.53 Direct F1, F5
transaction YMAB Employee Stock Option (right to buy) Disposed to Issuer -16K -100% 0 Sep 16, 2025 Common Stock 16K $16.64 Direct F1, F5
transaction YMAB Employee Stock Option (right to buy) Disposed to Issuer -14K -100% 0 Sep 16, 2025 Common Stock 14K $8.13 Direct F1, F5
transaction YMAB Employee Stock Option (right to buy) Disposed to Issuer -14.5K -100% 0 Sep 16, 2025 Common Stock 14.5K $12.01 Direct F1, F5
transaction YMAB Employee Stock Option (right to buy) Disposed to Issuer -33.5K -100% 0 Sep 16, 2025 Common Stock 33.5K $4.51 Direct F1, F5
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

David N. Gill is no longer subject to Section 16 filing requirements. Form 4 or Form 5 obligations may continue.

Explanation of Responses:

Id Content
F1 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").
F2 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.
F3 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.
F4 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.
F5 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.