Shares of Chimerix Inc., the maker of an experimental drug to combat Ebola, sank Wednesday after the death in Dallas of a patient with the disease who received the medicine.

About two hours after officials announced the death of Thomas Eric Duncan, the Durham, N.C., company’s stock was trading at $30.54, down $2.69, or 8.1%. The shares had hit an all-time high earlier in the day before the announcement.