Merck To Acquire Cidara Therapeutics
Merck to acquire Cidara strengthens its antiviral and respiratory pipeline ahead of Keytruda patent expiry and shifts near-term trader positioning.

KEY TAKEAWAYS
- Merck agreed to buy Cidara for $221.50 per share, valuing the deal at about $9.2 billion.
- It adds CD388, a late-stage influenza prevention drug-Fc conjugate, to Merck's respiratory antiviral pipeline.
- Merck expects the acquisition to help offset revenue pressure from Keytruda patent expiry; close expected Q1 2026.
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Merck & Co., Inc. (NYSE: MRK) said on Nov. 14, 2025, in a press release that it will acquire Cidara Therapeutics, Inc. (Nasdaq: CDTX) to strengthen its respiratory and antiviral pipeline as it prepares for the anticipated Keytruda patent expiry.
Deal Terms and Timing
Merck will acquire Cidara in a definitive, all-cash transaction priced at $221.50 per share, valuing the deal at about $9.2 billion. The companies expect to close the transaction in the first quarter of 2026, pending Cidara shareholder approval and customary regulatory reviews, including antitrust and SEC processes. Merck said it will account for the acquisition as an asset purchase.
Pipeline and Strategic Rationale
Cidara’s lead asset, CD388, is a drug–Fc conjugate developed for influenza prevention. The CD388 program reported positive topline results from its NAVIGATE Phase 2 study in June 2025 and began the ANCHOR Phase 3 study in September 2025. This late-stage antiviral asset is the primary clinical rationale for the acquisition.
Merck said the deal will accelerate its respiratory and antiviral portfolio expansion to address an expected revenue gap following Keytruda’s loss of exclusivity later this decade.





