Stocks open lower ahead of economic reports

NEW YORK (AP) ? Stocks are opening lower on Wall Street amid uncertainty over what authorities in the U.S., China and Europe might do to help the slowing world economy.

The Dow Jones industrial average was down 13 points at 13,076 shortly after the opening bell on Tuesday. The U.S. stock market was closed Monday for Labor Day. The broader S&P 500 index fell one point to 1,405. Nasdaq edged lower by three points to 3,064.

In Europe, Moody’s warned that it could downgrade the credit rating of the European Union as a whole, citing the mounting strain of the continent’s debt crisis. That sent markets lower in Germany and France.

In the U.S., reports on August manufacturing and July construction spending are due out at 10 a.m. Eastern time.