The Raiders are negotiating to sell off another percentage of the team, this time to a billionaire who has been reportedly trying to buy a franchise with designs on moving it to Los Angeles. Chief executive Amy Trask has been spearheading negotiations with a group headed by C. Dean Metropoulos that would sell at least 10 percent stake in the Raiders. The Raiders sold 20 percent of the team in October 2007 to three businessmen to get more cash infusion, which is also the goal on the latest transactor, according to the sources.