Wall Street turns negative as IMF warns on Greece

U.S. stocks turned negative after the International Monetary Fund warned Greece may need a further large debt writeoff, and weak U.S. jobs data dampened the economic outlook. IMF's warning comes as Greece readies for a Sunday referendum on an international bailout deal that Prime Minister Alexis Tsipras has urged voters to reject. "The market seems to be paying more attention to what may happen with Greece as well as whether or not wage growth will pick up," said Omar Aguilar, chi