The broad-market indexes may be relatively flat for the year, but shareholders of pharmaceutical juggernaut Merck (NYSE:MRK) would just as soon kiss 2015 goodbye. As we saw last week, Merck's had quite a few exciting headlines in 2015 that could give investors plenty to look forward to in 2016 and beyond. Nonetheless, shares of Merck have declined in 2015 by more than 6% through the Christmas Day holiday.
