Shares of Canadian company Tekmira Pharmaceuticals surged on Friday after US officials loosened restrictions on the use of its experimental drug to treat the Ebola virus.
Near 1925 GMT, Tekmira shares were 36.1 percent higher at $19.42 a share.
Tekmira announced on Thursday that the US Food & Drug Administration had "verbally confirmed" that they shifted the classification of its TKM-Ebola treatment to a partial clinical hold from a full clinical hold.
"This action enables the potential use of TKM-Ebola in individuals infected with Ebola virus," the company said.
"This current outbreak underscores the critical need for effective therapeutic agents to treat the Ebola virus," said Tekmira chief executive Mark Murray.
"We recognize the heightened urgency of this situation, and are carefully evaluating options for use of our investigational drug within accepted clinical and regulatory protocols."
Two Americans infected with Ebola have shown signs of improvement since being given ZMapp, a treatment made by private US company Mapp Pharmaceuticals.
There is no proven treatment or cure for Ebola and the use of experimental drugs for treatment has sparked debate with the latest outbreak in West Africa.
Nearly 1,000 people have died in the new outbreak and the World Health Organization declared it a global health emergency on Friday.
WHO director-general Dr Margaret Chan appealed for greater help for those worst hit by the "largest, most severe and most complex outbreak in the nearly four-decade history of this disease."