Merck, known as MSD outside the United States and Canada, has announced the successful completion of its cash tender offer, through a subsidiary, to acquire Cidara Therapeutics, Inc.
The acquisition is aimed at strengthening Merck’s expanding respiratory portfolio, particularly through CD388, a potentially first-in-class, long-acting antiviral candidate with strain-agnostic properties for the prevention of influenza.
“Acquiring Cidara enhances our respiratory pipeline and reflects our strategy of investing where strong science and long-term value converge,” said Robert M. Davis, chairman and chief executive officer of Merck. “CD388 represents a promising approach to preventing symptomatic influenza in individuals at high risk of complications.”
Merck completed the tender offer at a purchase price of USD 221.50 per share of Cidara common stock, without interest and subject to applicable tax withholdings. As of the offer’s expiration shortly after midnight Eastern Time on January 6, 2026, approximately 27.15 million shares—representing around 85.96 per cent of Cidara’s outstanding common stock—had been validly tendered and accepted for payment.
The company plans to complete the acquisition through a merger of its wholly owned subsidiary with Cidara, with Cidara continuing as the surviving entity. Following the merger, all remaining shares not tendered will be converted into the right to receive the same cash consideration of USD 221.50 per share. Cidara will become a wholly owned subsidiary of Merck, and its shares will no longer trade on the Nasdaq Global Market.
Merck expects to account for the transaction as an asset acquisition, which will result in an increase in 2026 research and development expenses of approximately USD 9.0 billion, or around USD 3.65 per share, reflected in both GAAP and non-GAAP results. Earnings per share are expected to be negatively impacted by approximately USD 0.30 per share over the first 12 months, largely due to development and financing-related costs.
Influenza remains a major global health burden, infecting an estimated one billion people annually, with millions developing severe illness. Complications can include pneumonia, worsening of chronic diseases and, in severe cases, death.
CD388 is an investigational drug-Fc conjugate designed to provide long-acting antiviral protection against influenza A and B viruses. Unlike vaccines, its activity does not depend on an immune response, making it potentially effective across a broad range of patient populations, including those with compromised immunity. CD388 is currently being evaluated in a phase 3 clinical study involving individuals at higher risk of influenza-related complications.
