Merck&Co fell by 3% to trade at $68.28 by 14:43 (18:43 GMT) on Thursday on the NYSE exchange.
The volume of Merck&Co shares traded since the start of the session was 7.07M. Merck&Co has traded in a range of $68.28 to $70.53 on the day.
The stock has traded at $72.89 at its highest and $68.28 at its lowest during the past seven days.
