shares of merck  co inc mrk slid 145 to 10879 monday on what proved to be an allaround favorable trading session for the stock market with the sp 500 index spx rising 040 to 455464 and the dow jones industrial average djia rising 052 to 3541124 merck  co inc closed 1086 short of its 52week high 11965 which the company achieved on may 3rd the stock underperformed when compared to some of its competitors monday as johnson  johnson jnj rose 052 to 17108 and pfizer inc pfe rose 029 to 3751 trading volume 56 m remained 19 million below its 50day average volume of 75 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