The broader market also fell, but not as much.
The Dow Jones industrial average was down 46 points at 14,818 at midday Friday, a loss of 0.3 per cent. In the first four days of the week the Dow had risen 300 points, or 2 per cent.
The Standard & Poor's 500 fell nine points, or 0.6 per cent, to 1,583. The Nasdaq fell 19 points, also 0.6 per cent, to 3,280.
Halliburton and other energy companies fell sharply as the price of crude oil dropped $2 to $91 a barrel.
Miners including Barrick Gold and Newmont Mining fell as gold plunged below $1,500 an ounce, the lowest since July 2011.