Clinton and Trump's tightening race causes market jitters

By Amanda Becker and Emily Stephenson FORT LAUDERDALE, Fla./MIAMI (Reuters) - As Democrat Hillary Clinton and Republican Donald Trump pushed their closing arguments ahead of next week's U.S. presidential election, financial markets were rattled on Wednesday by opinion polls showing a tightening White House race. While most national polls still favor Clinton to win, she has lost the comfortable lead she held late last month and investors are starting to factor in the possibility that the New York