Merck reported quarterly sales that were slightly lower than expected, hurt by competition from cheaper generic medicines, and predicted full-year earnings at the lower end of analysts' expectations.
The second-biggest U.S. drugmaker said on Wednesday it earned $781 million, or 26 cents per share, in the fourth quarter. That compared with $908 million, or 30 cents per share, in the year-earlier period.
After the earnings announcement, the company's shares rose in premarket trading. (Click here to get the latest quotes for Merck.)
Revenue fell 4 percent to $11.32 billion. Wall Street was expecting $11.36 billion, according to Thomson Reuters.
Merck predicted full-year earnings, excluding special items, of $3.35 to $3.53 per share. The average analyst estimate was $3.48 per share.
—By Reuters. CNBC contributed to this report.