Five minutes into trade, the Dow Jones Industrial Average dipped 18.43 points (0.12 percent) to 15,991.56. The Dow closed Thursday above 16,000 for the first time, its latest in a series of landmarks signifying the bull run of 2013.
The broad-based S&P 500 inched up 0.43 (0.02 percent) to 1,796.28, while the tech-rich Nasdaq Composite Index rose 10.23 (0.26 percent) to 3,979.39.
The US economic calendar was fairly quiet, but the close German Ifo economic institute's business climate index rose to 109.3 in November from 107.7 in October. It was the highest reading in more than 18 months and well above analysts' estimates.