Key TakeawaysThe S&P 500 was little changed on Thursday, Aug. 29, following an upward revision to second-quarter economic growth figures.Best Buy shares soared as strength in tablets and computers helped the electronics retailer top sales and profit forecasts.Shares of Dollar General plummeted after the discount retailer's sales and profits fell short of estimates. Major U.S. equities indexes were mixed after a report showed that the U.S. gross domestic product (GDP) grew more than previously thought in the ...