Reebok picked the city's rapidly growing Seaport District for its new global headquarters in December, following in the footsteps of New Balance and Converse, both of which opened splashy new headquarters in 2015 that helped redefine the city skyline. Just outside the city limits, Wolverine World Wide Inc. - the Rockford, Michigan-based owners of Saucony, Keds, Sperry and other brands - opened a regional campus in Waltham for 370 workers this summer after moving it south from Lexington, Massachusetts. And The Rockport Group, purveyor of casual and dress shoes, is slated to christen a new headquarters for 212 employees in the affluent Boston suburb of Newton later in January. The company was sold in 2015 by Adidas AG, the German sportswear giant that still owns Reebok International Ltd., to a standalone company formed by New Balance Holdings Inc. and a private equity firm.