The Dow was off 94 points at 13,915 shortly after the opening bell Monday. Energy and health care stocks led the declines.
The stock market has been rallying for five weeks, and the Dow is still up more than 6 percent for the year. On Friday, the Dow closed above 14,000 for the first time in more than five years.
The Standard & Poor's 500 index fell eight points to 1,505 and the Nasdaq composite lost 15 points to 3,163.
Corporate earnings reports continue this week. Health insurer Humana rose 2.5 percent after its earnings beat Wall Street's forecasts.