Blackstone Group said Monday it is buying the 110-story building . The deal will allow Blackstone to expand its headquarters in New York City and create more than 1,000 jobs for local residents. It was renamed Willis Tower in 2009 after Willis North America , an insurance brokerage that is a tenant in the tower , bought naming rights . Purchase adds 3.8million square feet of space to New York-based Blackstone 's huge investment portfolio .
Blackstone Group said Monday it is buying the 110-story building . Formerly known as the Sears Tower , the building is the tenth tallest in the world . It was renamed Willis Tower in 2009 after Willis North America , an insurance brokerage that is a tenant in the tower , bought naming rights . Purchase adds 3.8million square feet of space to New York-based Blackstone 's huge investment portfolio .