Corcept Plunges on Review of Korlym Patent Sought by Teva

Corcept Therapeutics Inc. dropped after the U.S. Patent and Trademark Office said it would review the validity of a patent on its only approved drug, Korlym.

Shares fell the most since February 2018 after the office’s review board said it had instituted a review of the validity of a Corcept patent based on a challenge filed by Teva Pharmaceutical Industries Ltd. The stock was halted twice because of volatility and closed 22% lower at $13.22 in New York. At one point it was down as much as 34%, its worst intraday slide in more than five years.

The patent, issued ...