Wall Street's big short - President Donald J. Trump

By Gertrude Chavez-Dreyfuss and David Randall NEW YORK (Reuters) - Add the juggernaut that is Donald J. Trump to the list of what-ifs that is worrying Wall Street. A growing realization that the unpredictable New York real estate developer is in a position to win the Republican nomination and then battle Hillary Clinton for the White House in November's election has caused some investors to sell U.S. stocks. "As the market rarely feasts on lack of predictability - Trump represents a nightma