shares of merck  co inc mrk slumped 005 to 10988 monday on what proved to be an allaround positive trading session for the stock market with the sp 500 index spx rising 119 to 401981 and the dow jones industrial average djia rising 076 to 3362956 the stocks fall snapped a twoday winning streak merck  co inc closed 561 short of its 52week high 11549 which the company achieved on january 6th