NEW YORK (CNNMoney) -- U.S. stocks edged lower Monday, as Greece and Italy swap out leaders, and investors remain cautious about how much these transitions will help resolve Europe's debt crisis. "Europeans delivered the necessary policy response to avert a meltdown," said Marc Chandler, global head of currency strategy at Brown Brothers Harriman. "But, for sure, this is unlikely to be a silver bullet and many questions still remain."