Sears its naming rights to the building expired in 2003 it remained the Sears Tower until early 2009. In March 2009 London-based insurer Willis Group Holdings, Ltd., was given the building's naming rights to encourage them to occupy the building. The official renaming as the "Willis Tower" took place on Thursday, July 16, 2009, during a public ceremony hosted by Willis Group Holdings. In the 1990s, the company began divesting itself of many non-retail entities, which were detrimental to the company's bottom line. Sears spun off its financial services arm which included brokerage business Dean Witter Reynolds and Discover Card. It
Willis Tower unfinished World Trade Center to become the world's tallest building. The height was restricted by a limit imposed by the Federal Aviation Administration (FAA) to protect air traffic. The financing of the tower was provided by the Sears company. It was topped with two antennas to permit local television and radio broadcasts. Sears and the City of Chicago approved the design, and the first steel was put in place in April 1971. The structure was completed in May 1973. The construction cost about US$150 million at the time, equivalent to $ million in 2019. By comparison, Taipei 101, built in