A slide in technology companies dragged the stock market lower, erasing an early gain.
Facebook slumped 7% after announcing a two billion dollar acquisition of virtual reality company Oculus, its second big purchase in two months.
The initial public offering of the company behind the hit game "Candy Crush Saga" flopped. King Digital Entertainment dropped 16% on its first day of trading.
The Standard & Poor's 500 index fell 13 points, or 0.7%, to close at 1,852 . It had been up 10 points earlier.
The Dow Jones industrial average fell 98 points, or 0.6%, to 16,268. The technology-heavy Nasdaq composite fell 60 points, or 1.4%, to close at 4,173.
Bond prices rose. The yield on the 10-year Treasury note fell to 2.70%.