Merck Shares Surge 10% to Record High, Market Cap Reaches $366.9 Billion

Merck & Co. shares jumped 10 percent on the day, closing at an all-time high and lifting the pharmaceutical company's total market capitalization to $366.9 billion. The sharp gain underscores renewed investor confidence in the drugmaker, though no specific catalyst was disclosed. The move cements Merck's position among the largest U. S. pharmaceutical companies by value.