Merck Shares Drop 1.02% on $1.2B Volume Spike 58th in Market as Oncology and ADC Collaborations Intensify

Merck (MRK) closed August 28, 2025, down 1.02% amid a trading volume of $1.2 billion, a 35.02% increase from the prior day’s activity, ranking it 58th in market volume. The stock’s performance follows key developments in its oncology pipeline and strategic collaborations.

The pharmaceutical giant highlighted advancements in its targeted therapy portfolio, including encouraging Phase 1 results for its investigational KRAS G12C inhibitor MK-1084 in colorectal and non-small cell lung cancers. Merck also advanced its antibody-drug conjugate (ADC) candidates, such as zilovertamab vedotin and sacituzumab tirumotecan, while securing the 42nd FDA approval for KEYTRUDA in head and neck cancer. Collaborations with Daiichi Sankyo on late-stage trials for ifinatamab deruxtecan in esophageal, prostate, and small cell lung cancers further underscore its focus on expanding ADC capabilities.

Merck’s partnership with Daiichi Sankyo extended to the initiation of a Phase III study for HER3-DXd in breast cancer, a HER3-directed ADC showing promise in later-stage trials. The company also announced co-development rights to additional ADCs, reflecting its strategy to diversify beyond KEYTRUDA ahead of its 2028 patent expiry. These moves align with Merck’s broader efforts to strengthen its position in the competitive ADC market.

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