Stocks dropped on Friday, snapping a four-day winning streak, after news reports that Standard & Poor's would downgrade credit ratings on several euro-zone countries.

The Dow Jones industrial average <.DJI> was down 49.72 points, or 0.40 percent, at 12,421.30. The Standard & Poor's 500 Index <.SPX> was down 6.39 points, or 0.49 percent, at 1,289.11. The Nasdaq Composite Index <.IXIC> was down 13.76 points, or 0.51 percent, at 2,710.94.

For the week, the Dow rose 0.5 percent, the S&P gained 0.9 percent and the Nasdaq has risen 1.4 percent.

(Reporting By Ryan Vlastelica; Editing by Kenneth Barry)