The S&P 500 index had its biggest loss of the year.
The Dow Jones industrial average lost 108 points to close at 13,927 points Wednesday.
The Standard & Poor's 500 lost nearly 19 points, or 1.2 percent, to 1,511.
Caterpillar fell after reporting weaker sales in North America and Asia, dragging the Dow lower.
Three stocks fell for every one that rose on the New York Stock Exchange. Volume was 4.1 billion shares, slightly heavier than usual.