NEW YORK, Nov. 5 (Xinhua) -- U.S. stocks ended a session of volatile trading lower on Monday after Citigroup stoked credit fears with the announcement of more mortgage-related losses.

    Charles Prince resigned on Sunday as chairman and chief executive of Citigroup Inc, as the bank said it may write off 11 billion dollars of subprime mortgage losses, on top of a 6.5 billion dollars write-down last quarter.

    The Dow Jones Industrial Average closed down 51.7 points at 13,543.4. The S&P 500 was down 7.48 points to 1,502.17, while the Nasdaq Composite shed 15.20 points to 2,795.18.