A weak open on Wall Street on gloomy IMF forecast

Another dire prediction about global economic growth is sending stocks lower on Wall Street in early trading.

The U.S. corporate earnings season is also shaping up to be weakest in years.

The combination sent indexes slightly lower shortly after the opening bell Tuesday. The Dow Jones industrial average was off 20 points at 13,564. The Standard & Poor's 500 index lost two points to 1,454 and the Nasdaq gave up 10 points to 3,101.

The International Monetary Fund said the global economy is weakening and that the downturn afflicting developing nations has begun to spread.

After the closing bell, aluminum maker Alcoa becomes the first major U.S. company to report third-quarter results. Analysts are expecting earnings at S&P 500 companies to decline overall for the first time in three years.