09:05 AM EST, 11/14/2025 (MT Newswires) -- Merck ( MRK ) on Friday agreed to acquire immunotherapy developer Cidara Therapeutics ( CDTX ) in a deal worth about $9.2 billion as it aims to expand its respiratory portfolio.

A subsidiary of Merck ( MRK ) will launch a tender offer to purchase all shares of Cidara for $221.50 apiece in cash. Cidara's stock jumped 104% in the most recent premarket activity, while Merck ( MRK ) declined 1.3%.

The transaction, which requires approval from regulators, is expected to complete in the first quarter of 2026.

The deal will give Merck ( MRK ) access to Cidara's lead therapeutic candidate, CD388, for influenza prevention. The product, which has been granted a breakthrough therapy designation by the US Food and Drug Administration, is currently being evaluated in a phase 3 clinical study for patients who are at a higher risk of developing complications from influenza.

"This acquisition expands and complements our respiratory portfolio and pipeline," Merck Research Laboratories President Dr. Dean Li said in a statement.

Last week, Cidara reported a third-quarter net loss of $3.10 per share, up from a $2.45 loss the year before. At the end of September, the company had cash, cash equivalents, restricted cash and available-for-sale investments of $476.5 million.

"We continue to execute our science-led business development strategy, augmenting our pipeline with CD388," Merck ( MRK ) Chief Executive Robert Davis said. "We intend to build on the Cidara team's remarkable progress and are confident that CD388 has the potential to be another important driver of growth through the next decade, creating real value for shareholders."

In July, Merck ( MRK ) agreed to acquire UK-based biopharmaceutical company Verona Pharma (VRNA) in a deal worth roughly $10 billion to expand its cardio-pulmonary disease treatment portfolio.