Merck&Co fell by 3.02% to trade at $82.25 by 10:19 (14:19 GMT) on Thursday on the NYSE exchange.
The volume of Merck&Co shares traded since the start of the session was 2.37M. Merck&Co has traded in a range of $82.25 to $83.67 on the day.
The stock has traded at $87.0700 at its highest and $82.2100 at its lowest during the past seven days.
