US STOCKS-Wall St slumps; S&P set for biggest weekly loss since 2012 By: Reuters: Company News August 01, 2014 at 12:41 PM EDT * Indexes down: Dow 0.7 pct, S&P 0.7, Nasdaq 0.9 pct (Updates to afternoon trading) Read More >> Related Stocks: Gopro Inc Cl A Procter & Gamble Scientific Games Tesla, Inc.