Y-mAbs Therapeutics, Inc. to Be Acquired for $413.0M

SERB paid $8.60 per share in cash for all outstanding Y-mAbs common stock, representing an equity value of approximately $412 million as announced and aggregate consideration (including option and restricted stock unit cashouts) of approximately $413 million, which Parent funded through a combination of cash on hand and short-term financing. The offer price represented an approximately 105% premium to Y-mAbs' closing share price of $4.19 on August 4, 2025, the last full trading day before the merger agreement was signed, and an approximately 92% premium to the volume-weighted average price of Y-mAbs shares over the 90 trading days ending August 4, 2025. Y-mAbs' financial advisor, Centerview Partners, performed a discounted cash flow analysis using discount rates of 14.5% to 16.5%, cash flows from July 1, 2025 through December 31, 2050, a terminal decline rate of 20% per year, and credit for approximately $240 million of federal and $194 million of state net operating losses as of December 31, 2024, net of the estimated cost of assumed future equity raises of $75 million in 2026, $50 million in 2027, $100 million in 2028, $100 million in 2029, and $150 million in a later year per management's financing assumptions.

Strategic rationale focused on Y-mAbs' lead commercial asset DANYELZA (naxitamab-gqgk), the first FDA-approved treatment for relapsed or refractory high-risk neuroblastoma. SERB CEO Vanessa Wolfeler stated, "High-risk neuroblastoma is not only a rare and devastating pediatric cancer but also one of the most difficult to treat. DANYELZA is recognized as a critical treatment option for patients and expands the treatment pathways available to providers in an outpatient setting. Working together with the team from Y-mAbs, I believe we can continue generating data for this product, expand partnerships to additional oncology centers, and have a positive impact on the lives of more neuroblastoma patients and their families." SERB Chairman Jeremie Urbain said the acquisition "reflects another milestone in the execution of our growth strategy to build a leading global specialty pharma platform" and that "DANYELZA is an excellent strategic fit for SERB as it strengthens our existing rare oncology portfolio." Y-mAbs CEO Michael Rossi said the agreement with SERB "reflects the most attractive option available to Y-mAbs, providing significant, immediate and certain value to our stockholders," following what the Schedule 14D-9 describes as a roughly five-month strategic review in which Y-mAbs or Centerview contacted or held discussions with at least 36 potential counterparties, signed confidentiality agreements with six potential strategic acquirers and five potential RIT investors, and received competing offers from two counterparties (referred to in the filing as Party A through Party H) before SERB emerged as the only party willing to proceed on acceptable terms.

The merger agreement provided for a termination fee payable by Y-mAbs of $14.25 million, equal to approximately 3.46% of the implied equity value of the transaction, in the event Y-mAbs terminated to accept a superior proposal or under other specified circumstances. Y-mAbs stockholders holding approximately 16% of outstanding shares signed tender and support agreements committing to tender their shares. Closing was conditioned on a majority of outstanding shares being tendered and expiration or termination of the HSR Act antitrust waiting period; SERB was contractually obligated to commence the tender offer by August 19, 2025, and the companies had targeted a close by the fourth quarter of 2025, though the transaction in fact closed September 16, 2025, ahead of that target. Y-mAbs agreed to pay Centerview an aggregate fee of approximately $9.1 million for its financial advisory services, of which $1.5 million was payable upon delivery of its fairness opinion and the remainder contingent on closing.

Y-mAbs retained Centerview Partners as exclusive financial advisor, Cooley LLP as legal counsel, and Joele Frank, Wilkinson Brimmer Katcher as strategic communications advisor. SERB retained Rothschild & Co. as exclusive financial advisor, Freshfields US LLP as legal counsel, and H/Advisors Abernathy as strategic communications advisor. At the effective time, outstanding Y-mAbs stock options with exercise prices below $8.60 were cancelled and converted into the right to receive cash equal to the spread, out-of-the-money options were cancelled for no consideration, and restricted stock units and performance stock units were cancelled and converted into cash based on the $8.60 merger consideration (with PSUs cashed out at maximum share levels). Following the merger, all of Y-mAbs' incumbent directors (Thomas Gad, David N. Gill, Laura J. Hamill, James I. Healy, Michael Rossi, Ashutosh Tyagi and Johan Wedell-Wedellsborg) and several executive officers, including CEO Michael Rossi, resigned in connection with the transaction.