The price of copper, a key commodity that's widely used in construction and manufacturing, slumped to a five-year low Wednesday.
The World Bank forecast that that global economic growth this year won't be as high as previously thought. The U.S. Commerce Department reported a drop in retail last month.
The Dow Jones industrial average was down 223 points, or 1.3 per cent, to 17,393 as of 9:35 a.m. Eastern time.
The Standard & Poor's 500 index fell 19 points, 0.9 per cent, to 2,004. The Nasdaq composite fell 37 points, or 0.8 per cent, to 4,625.
Bond prices rose. The yield on the 10-year Treasury note dropped to 1.82 per cent.