U.S. stocks tumbled on Monday as the credit outlook of the United States was downgraded, with the Dow losing 2 percent. China added to global economic worries by curbing liquidity.

The Dow Jones industrial average <.DJI> dropped 240.14 points, or 1.95 percent, to 12,101.69. The Standard & Poor's 500 Index <.SPX> dropped 24.34 points, or 1.84 percent, to 1,295.34. The Nasdaq Composite Index <.IXIC> dropped 56.44 points, or 2.04 percent, to 2,708.21.

(Editing by Kenneth Barry)