U.S. stocks end mixed in volatile trading

NEW YORK, May 20 (Xinhua) -- U.S. stocks closed mixed in choppy trading on Friday as investor sentiment remained shaky on Wall Street.

The Dow Jones Industrial Average increased 8.77 points, or 0.03 percent, to 31,261.90. The S&P 500 added 0.57 points, or 0.01 percent, to 3,901.36. The Nasdaq Composite Index fell 33.88 points, or 0.30 percent, to 11,354.62.