US STOCKS-Wall St tumbles; Dow, S&P turn negative for July By: Reuters: Company News July 31, 2014 at 10:12 AM EDT * Indexes down: Dow 0.7 pct, S&P 0.8 pct, Nasdaq 0.9 pct (Updates to open, adds Chicago PMI data) Read More >> Related Stocks: Cigna Corp Exxon Mobil Time Warner Cable Whole Foods Market