shares of carmax inc kmx slid 199 to 11867 monday on what proved to be an allaround rough trading session for the stock market with the sp 500 index spx falling 014 to 467029 and dow jones industrial average djia falling 045 to 3606887 carmax inc closed 3731 below its 52week high 15598 which the company achieved on november 8th the stock underperformed when compared to some of its competitors monday as copart inc cprt fell 023 to 13609 autonation inc an rose 333 to 11636 and penske automotive group inc pag fell 020 to 10684 trading volume 13 m eclipsed its 50day average volume of 12 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