NEW YORK, March 21 (Reuters) - Biogen Inc on Tuesday won an intellectual property rights ruling against hedge fund manager Kyle Bass over its top multiple sclerosis pill, Tecfidera, pushing shares up more than 1 percent on a day when most U.S. stocks were down.
The ruling came from the U.S. Patent and Trademark Office's Patent Trial and Appeal Board in Washington.
The decision should extend the time that Biogen can keep U.S. sales of the drug out of the hands of generic competitors by four to five years, according to Mizuho analyst Salim Syed.
Bass could appeal the ruling, Syed said in a research note.
Neither Bass nor Biogen were immediately available for comment.
The hedge fund manager's legal challenge centered on the so-called 514 patent, which focuses on a method for dosing multiple sclerosis patients with 480 milligrams per day of certain fumarates, which are chemical intermediates.
Bass has filed a number of lawsuits against multiple companies as part of an effort to eliminate drug patents that he believed were being improperly extended based on dosing schedules, preventing cheaper drugs from hitting the market.
Biogen shares rose $4.12, or 1.5 percent, to $278.92 in early afternoon Nasdaq trading. The Dow Jones Industrial Average , S&P 500 and Nasdaq Composite were all down.
(Reporting by Caroline Humer; Editing by Jonathan Oatis)