The dollar rebounded Thursday, a day after plunging against the euro.
Exxon Mobil and Chevron were among the biggest decliners in the Dow Jones industrial average.
The Dow welcomed its newest member, Apple, on Thursday. The iPhone maker took the place of AT&T.
The Dow was down 127 points, or 0.7 per cent, to 17,948 as of 11:45 a.m. Eastern.
The Standard & Poor's 500 fell 12 points, or 0.6 per cent, to 2,087. The Nasdaq edged up four points, or 0.1 per cent, to 4,987.
Crude oil fell 92 cents to $45.73 a barrel.
Bond prices fell. The yield on the 10-year Treasury note rose to 1.95 per cent.