U.S. Stocks Open Sharply Lower As Greece Faces Default

U.S. stocks began the holiday-shortened week with sharp declines on Monday, as global equity markets were hit by the unraveling crisis in Greece. The country's Prime Minister Alexis Tsipras unexpectedly called for a referendum on whether to accept reform measures demanded by the country's lenders. The S&P 500 opened 18 points, or 0.9%, lower at 2,082. The Dow Jones Industrial Average dropped 160 points, or 0.9%, to 17,784. The Nasdaq Composite began the day down 61 points, or 1.2% at 5,019.