Merck (MRK) Stock After Hours Today (Dec. 22, 2025): Why Shares Jumped and What to Watch Before Tuesday’s Open
Merck & Co. (NYSE: MRK) is ending Monday’s session with fresh momentum—and investors heading into Tuesday’s open (Dec. 23, 2025) have a lot to digest. After a strong regular-session rally, Merck stock closed at $104.72, up $3.63 (+3.59%), and traded