U.S. stocks plunged for the third day this week after Bear Stearns Cos. required a bailout from the Federal Reserve and JPMorgan Chase & Co. to avoid collapse. The S&P 500 retreated 27.34, or 2.1 percent, to 1,288.14 and slid 0.4 percent in the week. The Dow Jones Industrial Average lost 194.65, or 1.6 percent, to 11,951.09. The Nasdaq Composite Index decreased 51.12, or 2.3 percent, to 2,212.49. Nine stocks fell for every one that rose on the New York Stock Exchange.