Move over Ken, Barbie has a new suitor.New York-based investment company Barington Capital Group has built an undisclosed stake in Barbie-owner Mattel and wants to swoop in to create value for shareholders, according to a letter sent to Mattel chief Ynon Kreiz.The activist investor said Mattel’s share price — which has hovered at around $18 and despite the smash success of the “Barbie” movie — will continue to underperform, according to the press release issued by Barington CEO James Mitarotonda,Mitarotond ...