Merck (MRK) Stock After Hours Today (Dec. 22, 2025): Why Shares Jumped and What to Watch Before Tuesday’s Open
Merck shares closed Monday at $104.72, up 3.59%, after a rally that put the stock within 1% of its 52-week high. Volume reached about 17.1 million shares. The move followed news that the White House struck new Most Favored Nation drug-pricing agreements with Merck and other firms, easing policy uncertainty cited by analysts.