The Standard & Poor's 500 index fell five points, or 0.3 per cent, to 1,872 as of noon Eastern time Monday.
The Dow Jones industrial average lost 76 points, or 0.5 per cent, to 16,375. The Nasdaq composite fell 11 points, or 0.3 per cent, to 4,324.
Investors were discouraged by an 18 per cent slump in Chinese exports last month, the latest sign of trouble for the world's second-largest economy. Japan lowered its estimate for fourth-quarter economic growth.
In the U.S., Chiquita Brands jumped 12 per cent after announcing it had agreed to combine with an Irish fruit supply company.
In bond trading, the yield on the 10-year Treasury note held steady at 2.79 per cent.