| Name | Relationship | Address | Signature | Signature date | CIK |
|---|---|---|---|---|---|
| Rossi Michael J | PRESIDENT & CEO, Director | C/O Y-MABS THERAPEUTICS, INC., 202 CARNEGIE CENTER, SUITE 301, PRINCETON | /s/ John LaRocca, Attorney-in-Fact | 18 Sep 2025 | 0001948795 |
| Type | Sym | Class | Transaction | Value $ | Shares | Change % | * Price $ | Shares After | Date | Ownership | Footnotes |
|---|---|---|---|---|---|---|---|---|---|---|---|
| transaction | YMAB | Common Stock | Disposition pursuant to a tender of shares in a change of control transaction | -$68.6K | -7.98K | -100% | $8.60 | 0 | 16 Sep 2025 | Direct | F1, F2 |
| transaction | YMAB | Common Stock | Disposed to Issuer | -129K | -100% | 0 | 16 Sep 2025 | Direct | F1, F3, F4 |
| 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 | -615K | -100% | 0 | 16 Sep 2025 | Common Stock | 615K | $5.75 | Direct | F1, F5 | ||
| transaction | YMAB | Employee Stock Option (right to buy) | Disposed to Issuer | -214K | -100% | 0 | 16 Sep 2025 | Common Stock | 214K | $14.36 | Direct | F1, F5 | ||
| transaction | YMAB | Employee Stock Option (right to buy) | Disposed to Issuer | -211K | -100% | 0 | 16 Sep 2025 | Common Stock | 211K | $6.16 | Direct | F1, F5 | ||
| transaction | YMAB | Restricted Stock Units | Disposed to Issuer | -18K | -100% | 0 | 16 Sep 2025 | Common Stock | 18K | Direct | F1, F6, F7 | |||
| transaction | YMAB | Restricted Stock Units | Disposed to Issuer | -18K | -100% | 0 | 16 Sep 2025 | Common Stock | 18K | Direct | F1, F6, F7 | |||
| transaction | YMAB | Restricted Stock Units | Disposed to Issuer | -18K | -100% | 0 | 16 Sep 2025 | Common Stock | 18K | Direct | F1, F6, F7 | |||
| transaction | YMAB | Restricted Stock Units | Disposed to Issuer | -52.7K | -100% | 0 | 16 Sep 2025 | Common Stock | 52.7K | Direct | F1, F6, F7 | |||
| transaction | YMAB | Restricted Stock Units | Disposed to Issuer | -52.7K | -100% | 0 | 16 Sep 2025 | Common Stock | 52.7K | Direct | F1, F6, F7 |
Michael J. Rossi is no longer subject to Section 16 filing requirements. Form 4 or Form 5 obligations may continue.
| 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. |
| F6 | 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. |
| F7 | 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. |
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.