MGM MIRAGE, the second-largest U.S. casino owner whose stock is down 25 percent in the past month, said its board approved a plan to buy back as many as 10 million shares, or 6.4 percent of its outstanding common stock.

MGM MIRAGE will buy the shares from time to time on the open market or in third-party transactions, the Las Vegas-based company said today. The owner of casinos including the Bellagio and MGM Grand completed a 10 million share buyback last year.

Shares of MGM MIRAGE, which is controlled by billionaire Kirk Kerkorian, have fallen after the company said gamblers from the United States were spending less at its casinos. The company has about 157.2 million shares outstanding and is second in size to Park Place Entertainment Corp.