sentences:  A reorganization of the group, completed in February 2006, created Seibu Holdings to act as a holding company for both the railway and Prince Hotels.Cerberus Capital Management, an American investment fund, became the largest shareholder in Seibu Holdings with a 29.9% share of the new company.In late 2012 and early 2013, Cerberus proposed that Seibu Railway abolish five non-core lines, along with other restructuring measures throughout the Seibu Holdings group, but management refused to implement these changes.