The strategic rationale centers on RAPT's lead asset, ozureprubart, a long-acting anti-IgE monoclonal antibody in Phase IIb development for prophylactic protection against food allergens. GSK's Chief Scientific Officer, Tony Wood, said: "The addition of ozureprubart brings another promising new, potential best-in-class treatment to GSK's pipeline... Ozureprubart offers the opportunity to bring sustained protection to patients with dosing every 12 weeks, and is consistent with our approach to acquire assets that address validated targets and where there is clear unmet medical need." RAPT's President and CEO, Brian Wong, said the deal "offers an attractive path forward for our programs, particularly the opportunity we envision for ozureprubart in food allergy" and would provide "access to the global development and commercialisation capabilities, resources and infrastructure that GSK has to offer." The transaction gives GSK global rights to ozureprubart excluding mainland China, Macau, Taiwan and Hong Kong; GSK assumes responsibility for success-based milestone and royalty payments owed to RAPT's China-market partner, Shanghai Jeyou Pharmaceutical Co., Ltd.
Under the terms of the agreement, GSK paid $58.00 per RAPT share in cash. GSK stated the purchase price would be funded entirely with cash on hand, with no external debt financing and no financing condition attached to the offer. As a clinical-stage biopharmaceutical company with no material revenue, RAPT's valuation was assessed using a discounted cash flow analysis rather than revenue or EBITDA multiples; J.P. Morgan, the company's financial advisor, modeled unlevered free cash flows for fiscal years 2026 through 2047 based on management projections, discounted at rates of 12.0% to 14.0%, adjusted for an assumed net cash position of $390 million as of December 31, 2025, dilution from assumed future equity raises, and tax savings from net operating losses of $318 million as of December 31, 2024. This analysis produced an implied equity value range of $49.45 to $62.05 per share, which J.P. Morgan compared to the $58.00 offer price.
The $58.00 per share offer price represented an approximately 65% premium to RAPT's $35.10 closing price on January 16, 2026 (the last trading day before signing), a 70% premium to the 30-day volume-weighted average price, a 97% premium to the 90-day volume-weighted average price, and a 58% premium to the highest closing price in the preceding 52 weeks. According to RAPT's Schedule 14D-9, GSK's offer progressed through three increases during negotiations: an initial non-binding proposal of $50.00 per share in cash on December 22, 2025; a revised proposal of $53.00 per share in cash plus a $4.00 per share contingent value right (CVR) tied to initiation of a pivotal Phase 3 trial of ozureprubart in food allergy by year-end 2027, submitted December 23, 2025; a further revised proposal of $55.50 per share in cash plus a CVR on December 30, 2025; and finally $58.00 per share in cash with no CVR, which RAPT's board viewed as reducing risk to stockholders relative to the earlier offers' contingent consideration.
J.P. Morgan rendered a fairness opinion to RAPT's board on January 19, 2026, concluding the offer price was fair, from a financial point of view, to RAPT stockholders. Per the Schedule 14D-9's "Background of the Offer" narrative, GSK first approached RAPT in September 2025 regarding ozureprubart partnering, with discussions evolving toward an acquisition proposal by December 2025. At the board's direction, J.P. Morgan contacted eight other potential strategic counterparties to solicit competing interest; one unnamed publicly traded global pharmaceutical company ("Party A") received a management presentation but did not submit a proposal, and all others formally declined or did not respond. The board concluded GSK's $58.00 per share, all-cash offer represented the highest value reasonably obtainable and the best alternative available to stockholders, citing certainty of value, the absence of financing conditions, and the results of the market check.
The merger agreement specifies a termination fee payable by RAPT to GSK of $78,400,000 under specified circumstances, such as RAPT's board changing its recommendation or accepting a superior proposal. The deal closed within the first quarter of 2026 as the parties had targeted, following a cash tender offer that commenced February 2, 2026 and expired March 2, 2026, subject to a minimum tender condition and clearance under the Hart-Scott-Rodino Antitrust Improvements Act; the original closing 8-K confirms the HSR waiting period requirement was satisfied as a condition of the merger's completion. In connection with closing, RAPT's common stock was delisted from Nasdaq and its outstanding equity awards (options, RSUs and warrants) were cancelled and converted into cash-based rights tied to the $58.00 merger consideration, with certain post-March-2025 equity grants subject to a vesting schedule (50% at closing, 50% nine months later or upon an involuntary termination, if earlier).
Evercore served as exclusive financial advisor and A&O Shearman served as legal counsel to GSK. J.P. Morgan Securities LLC served as exclusive financial advisor and Cooley LLP served as legal counsel to RAPT Therapeutics.