ウィリス・タワー
Although Sears' naming rights expired in 2003, the building continued to be called the Sears Tower for several years, despite multiple changes in ownership. In March 2009, London-based insurance broker Willis Group Holdings agreed to lease a portion of the building and obtained the naming rights. On July 16, 2009, the building was officially renamed Willis Tower. On August 13, 2012, United Airlines announced it would move its corporate headquarters from 77 West Wacker Drive to Willis Tower.