shares of american express co axp slid 157 to 15929 wednesday on what proved to be an allaround grim trading session for the stock market with the sp 500 index spx falling 041 to 409195 and dow jones industrial average djia falling 011 to 3364650 the stocks fall snapped a twoday winning streak american express co closed 3313 below its 52week high 19242 which the company achieved on april 21st the stock underperformed when compared to some of its competitors wednesday as jpmorgan chase  co