shares of norfolk southern corp nsc slid 171 to 20390 friday on what proved to be an allaround grim trading session for the stock market with the sp 500 index spx falling 110 to 391664 and dow jones industrial average djia falling 119 to 3186198 norfolk southern corp closed 8765 below its 52week high 29155 which the company achieved on march 31st the stock underperformed when compared to some of its competitors friday as union pacific corp unp fell 150 to 19001 trading volume 27 m eclipsed its 50day average volume of 17 m editors note this story was autogenerated by automated insights an automation technology provider using data from dow jones and factset see our market data terms of use