Merck Shares Drop on Pipeline Setback Despite Positive Drug Updates

Merck & Co. (MRK) shares dropped 3.5% on October 5, 2026, amid investor caution following a recent pipeline setback. The decline appears linked to the voluntary withdrawal of the U.S. application for ifinatamab deruxtecan in previously treated extensive-stage small cell lung cancer, announced late last month. With no new negative company news on the day, the price movement may also reflect profit-taking as traders weigh this setback against several recent positive updates.

Merck disclosed on September 25 that the biologics license application for ifinatamab deruxtecan was withdrawn after discussions with the FDA regarding the data package supporting accelerated approval. However, the company also reported positive developments, including tulisokibart meeting primary and key secondary endpoints in a Phase 2b study for hidradenitis suppurativa. Additionally, the FDA approved Welireg plus Lenvima on September 24 for certain previously treated adults with advanced renal cell carcinoma, expanding Merck’s oncology portfolio.

The mix of one significant setback and multiple positive updates suggests the stock’s decline could be driven by sentiment rather than a broad deterioration in Merck’s underlying business. Analysts have issued varying price targets for MRK, with a median target of $141.0 based on recent assessments.