shares of merck  co inc mrk were unchanged wednesday on what proved to be an allaround positive trading session for the stock market with the sp 500 index spx rising 024 to 456572 and the dow jones industrial average djia rising 031 to 3506121 merck  co inc closed 1370 below its 52week high 11965 which the company reached on may 3rd the stock demonstrated a mixed performance when compared to some of its competitors wednesday as johnson  johnson jnj fell 020 to 15874 and pfizer inc pfe rose 055 to 3644 trading volume 66 m remained 777000 below its 50day average volume of 74 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