Wendy’s shares jumped 15% at the opening bell on Wednesday after investor Nelson Peltz’s Trian Fund Management and its partners offered to take the burger chain private, putting a struggling fast food business back in the spotlight, The Associated Press reported.The group has offered $7.35 a share in cash, a premium of nearly 19% to Wendy’s Tuesday closing price. Trian’s stake in the company stands at 16.3%, according to a regulatory filing cited by AP.The bid comes as Wendy’s faces a difficult operating environment, with high beef and other commodity costs, pressure on lower income consumers and intensifying competition in the US burger market.For live updates on US Markets, click hereWendy’s tries to regain groundWendy’s has been losing ground to rivals as the fast food market becomes more crowded.