U.S. stocks opened the week lower after the latest setback in Middle East peace talks coincided with a deepening selloff in U.S. Treasurys. The S&P 500 fell 59.7 points, or 0.77%, to 7683.69. The Dow Jones Industrial Average dropped 347.1 points, or 0.67%, to 51481.51, while the Nasdaq Composite declined 248.3 points, or 0.92%, to 26820.38.