Wall Street pares gains after Yellen cautions about economy

Wall Street gave up some gains on Tuesday after Federal Reserve Chair Janet Yellen said the central bank would be cautious in raising interest rates given risks such as Britain's membership in the European Union and a slowdown in the U.S. labor market. "The pace of improvement in the labor market appears to have slowed more recently, suggesting that our cautious approach ... remains appropriate," Yellen said. The central bank left interest rates unchanged and cut the economy's growth forecast la