Merck&Co fell by 3.02% to trade at $68.41 by 09:31 (13:31 GMT) on Thursday on the NYSE exchange.
The volume of Merck&Co shares traded since the start of the session was 1.50M. Merck&Co has traded in a range of $66.35 to $68.77 on the day.
The stock has traded at $73.4900 at its highest and $66.5300 at its lowest during the past seven days.
