U.S. stocks slid at the open on Monday after Standard & Poor's downgraded the credit outlook for the United States to negative.

The Dow Jones industrial average <.DJI> dropped 177.25 points, or 1.44 percent, to 12,164.58. The Standard & Poor's 500 Index <.SPX> fell 19.35 points, or 1.47 percent, to 1,300.33. The Nasdaq Composite Index <.IXIC> lost 41.14 points, or 1.49 percent, to 2,723.51.

The rating agency said it believes there's a risk U.S. policymakers may not reach agreement on how to address the country's long-term fiscal pressures.

(Editing by Kenneth Barry)