Merck Clears Antitrust Hurdle for Terns Acquisition, BD Cadence Continues

What happened

Merck announced the expiration of the HSR waiting period for its $6.7B acquisition of Terns Pharmaceuticals, clearing a key regulatory step. The deal is part of Merck’s strategy to diversify its pipeline ahead of the Keytruda loss-of-exclusivity in 2028-2029. However, the acquisition will not materially impact 2026 financials given the $9B Cidara IPR&D charge already guided and the time to commercialize Terns' assets. The market reaction is likely muted as investor focus remains on the Gardasil China shipment pause and the quantified $2.5B 2026 headwind. This step forward does not alter the near-term risk profile, which centers on execution of the post-Keytruda build.

Implication

Long-term, the Terns acquisition adds a potential obesity/endocrine candidate to Merck's pipeline, supporting the post-Keytruda build. However, the $6.7B price and IPR&D charges pressure near-term earnings. Success hinges on clinical data and commercial execution, not just regulatory clearance.

Thesis delta

The thesis remains WAIT; the Terns HSR expiration is a procedural step that doesn't shift the investment narrative. The key catalysts remain the Keytruda PDUFA date (April 28), Gardasil China restart visibility, and the FY2026 headwind containment. Until those show improvement, the stock stays range-bound.