US STOCKS-Oil slump leads Wall St to worst week in 2-1/2 years By: Reuters: Company News December 12, 2014 at 16:29 PM EST * Indexes off: Dow 1.8 percent, S&P 1.6 percent, Nasdaq 1.2 percent (Updates to close) Read More >> Related Stocks: Adobe Systems Chemocentryx Inc Chevron Corp Exxon Mobil