Cidara Therapeutics Stock (CDTX) Doubles on Merck Acquisition News

Cidara Therapeutics stock (CDTX) is on the move this morning, up 104% at $216.63 following news of its acquisition by Merck (MRK). The deal, valued at approximately $9.2 billion, equates to $221.50 per share in cash, marking a substantial premium for Cidara stockholders.

This rise reflects the market's positive assessment of the deal's value for Cidara shareholders. In contrast, Merck's shares saw a modest decline of 0.8%, with broader markets lower into the open.

Under the terms of the agreement, Merck, through a subsidiary, will acquire all outstanding shares of Cidara. The acquisition is contingent upon a majority of Cidara's stockholders tendering their shares in a tender offer initiated by Merck's subsidiary. The closing of the transaction is subject to customary conditions, including the expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act, and is anticipated to occur in the first quarter of 2026. The transaction is expected to be accounted for as an asset acquisition.

Cidara's leading asset, CD388, an experimental drug for the prevention of influenza A and B in high-risk individuals, played a crucial role in attracting Merck's interest. The FDA granted CD388 “breakthrough therapy” designation in October 2025, highlighting its potential to address a significant unmet medical need and expediting its development and review process. This designation underscores the drug's promise and likely contributed to Merck's decision to acquire Cidara.

For Merck, the acquisition of Cidara aligns with a broader strategy to diversify its portfolio and mitigate potential revenue declines associated with the impending loss of patent protection for its blockbuster cancer drug, Keytruda, by 2028. By adding Cidara's innovative influenza treatment to its pipeline, Merck aims to fortify its presence in the infectious disease market and capitalize on the growing demand for effective preventative therapies.

A great day for CDTX bulls comes on the back of an already strong year for the stock, with gains of 288% already booked leading into today's double.