• 08 Jan 2026
• Admin
• News Article

Merck Completes Acquisition of Cidara Therapeutics, Strengthening Its Influenza Pipeline

Merck (known as MSD outside the US and Canada) has successfully completed its cash tender offer to acquire Cidara Therapeutics, marking a major expansion of its respiratory disease portfolio.

The deal brings CD388, a potentially first-in-class, long-acting antiviral for influenza prevention, fully under Merck’s control.

Deal Snapshot: What Merck Acquired

• Offer price: $221.50 per Cidara share (all-cash)
• Shares tendered: 27.15 million
• Acceptance rate: ~86% of outstanding shares
• Transaction structure: Merger following tender offer
• Status: Cidara becomes a wholly owned subsidiary of Merck
• Nasdaq listing: To be discontinued

All remaining untendered shares will be converted to cash at the same offer price.

Financial Impact for Merck

Merck expects to account for the transaction as an asset acquisition.

Key financial effects

• ~$9.0 billion increase in 2026 R&D expenses
• Approx. $3.65 per share impact
• GAAP and non-GAAP EPS reduction of ~$0.30 per share over the first 12 months
  (driven by CD388 development and financing costs)

Why Merck Bought Cidara: The CD388 Thesis

At the center of the acquisition is CD388, a novel antiviral designed to prevent influenza in people at high risk of complications.

What makes CD388 different?

• Investigational drug–Fc conjugate (DFC)
• Long-acting, strain-agnostic antiviral activity
• Targets influenza A and B, including pandemic-risk strains
• Designed for season-long protection
• Not a vaccine and not an antibody
• Efficacy does not depend on immune response

This makes CD388 particularly relevant for:

• Elderly populations
• Immunocompromised patients
• Individuals with chronic conditions

Clinical Status of CD388

• Trial: Phase 3 ANCHOR study (NCT07159763)
• Population: Adults and adolescents at high risk of influenza complications
• Goal: Prevention of symptomatic influenza

If successful, CD388 could redefine prophylactic flu protection beyond traditional vaccines.

Influenza: A Persistent Global Burden

Despite vaccines and antivirals, influenza remains a major unmet medical need.

Global impact

• ~1 billion infections annually
• 3–5 million severe cases
• 290,000–650,000 deaths each year worldwide
• Up to 52,000 deaths annually in the US

Merck is clearly betting that long-acting, non–immune-dependent antivirals can fill critical gaps in prevention.

Strategic Fit for Merck

“This acquisition strengthens and complements our expanding respiratory portfolio,” said Robert M. Davis, Merck’s Chairman and CEO.

The deal reflects Merck’s broader strategy:

• Invest in compelling science
• Target large, underserved markets
• Build durable franchises in infectious diseases

Bottom Line

Merck’s acquisition of Cidara is not just an M&A event—it is a strategic commitment to next-generation influenza prevention.

If CD388 delivers in Phase 3, Merck could emerge with:

• A first-in-class, long-acting flu antiviral
• A powerful complement—or alternative—to vaccines
• A differentiated asset for high-risk populations

This is a bold, expensive move—but one squarely aligned with Merck’s long-term respiratory ambitions.