's economy and signs that the Federal Reserve might curtail its bond-buying program.
The Dow Jones industrial average was down 48 points at 13,878 shortly after the opening bell Thursday.
The Standard & Poor's 500 fell seven to 1,504. The Nasdaq lost 11 points to 3,152.
European markets also fell.
Business in the European Union slowed in February, suggesting that a downturn that began last year will continue into 2013. A monthly purchasing managers' index from financial information company Markit fell, missing analysts' forecasts.
In the U.S., the Labor Department reported that the number of people applying for unemployment benefits jumped last week. The four-week average rose to the highest in six weeks.