Traders work on the floor of the New York Stock Exchange on August 25, 2008 in New York City. Wall Street returns from vacation season to enter what is historically the most perilous period of the year amid conflicting signals about the US economic outlook.(AFP/Getty Images/File/Mario Tama)AFP - Wall Street returns from vacation season to enter what is historically the most perilous period of the year amid conflicting signals about the US economic outlook.