A rally sparked by Donald Trump's surprise victory in the U.S. presidential election, that also powered the Dow to a record high, sputtered on Friday as energy and healthcare stocks came under pressure.
Investors scrambled to adjust their portfolios to benefit from Trump's plans to simplify regulation in the health and financial sectors and boost spending on infrastructure.
The S&P 500 financial index has gained 7.2 percent, industrials 4.1 percent and healthcare 2.9 percent since the U.S. election on Tuesday, far outperforming other sectors.
The S&P is on track to mark its best week since October 2014, despite the pull back on Friday.
"The market this week has been exceptionally strong and when you see a massive rally like this, it is perfectly normal to see some profit-taking," said Adam Sarhan, chief executive of 50 Park Investments.
"The market has earned the right to pause a little bit to digest that move."
Oil prices fell more than 3 percent as the market refocused on a persistent supply overhang that is not expected to abate unless OPEC and other producers cut their output significantly.
Eight of the 11 major S&P 500 sectors were lower, with declines in energy and health being the steepest.
At 11:06 a.m. ET the Dow Jones industrial average was down 41.78 points, or 0.22 percent, at 18,766.1.
The S&P 500 was down 11.23 points, or 0.52 percent, at 2,156.25 and the Nasdaq Composite was down 10.92 points, or 0.21 percent, at 5,197.88.