In late 2019, Merck & Co.’s stock price fell significantly due to a number of factors. The most immediate cause was the release of their third quarter earnings report that showed disappointing numbers; this led to a drop in the company’s overall share price on the day it was released. However, this initial decline was only the beginning as news quickly spread about potential issues with their drug Keytruda, which is used to treat certain types of cancers and other illnesses.

The Food and Drug Administration (FDA) had made changes to its prescribing information for Keytruda that raised safety concerns among many investors who worried that sales would be affected by these changes as they could potentially limit usage of the drug or result in stricter regulations being imposed on it going forward. In addition, some analysts felt Merck & Co.’s pipeline lacked sufficient innovation in comparison to other companies such as Pfizer Inc., which indicates that future growth may not match up with current estimates.