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NEW YORK (CNNMoney.com) -- Chicago's landmark Sears Tower, the tallest building in the Western Hemisphere, will be renamed Willis Tower after insurance broker Willis Group Holdings, the company announced Thursday.

"Willis Tower will make us a household name among our clients, prospective clients and in the larger business community," said Don Bailey, chairman and chief executive of Willis HRH, the company's North American business.

The London, England-based company said it will rent 140,000 square feet of the building at a cost of $14.50 per square foot. The move, which involves 500 employees and consolidating five area offices, is expected to be completed by late summer.

"We found a great opportunity, a great deal, in the Sears Tower," Joseph Plumeri, chairman and chief executive of the Willis Group, told CNN.

Willis Group Holdings (WSH) provides insurance, risk management, financial and human resource consulting to corporations and public institutions around the world.

"This key new tenant underscores the importance of the building as a destination for successful businesses," said John Huston, of American Landmark Properties, Ltd., one of the investors that owns the tower, in a written statement.

Rita Athas, executive director of World Business Chicago, a not-for-profit economic development corporation, said the move demonstrates the Willis Group's commitment to the city and could boost the labor market there.

"Their decision speaks to the quality of Chicago's workforce, and our vibrant and supportive business community," Athas said in a written statement.

While the company expects to rechristen the building sometime this summer, it's not clear whether the new name will stick with native Chicagoans.

"The Sears Tower has been an icon here for the last quarter of a century," said John Russick, senior curator at the Chicago Historical Society. "For the generation that grew up calling it the Sears Tower, it'll be hard for people to shift and start calling it something else," he said.

Indeed, many long-time Chicago residents still refer to the Standard Oil Building, now know as the Aon Center, as "Big Stan" Russick said. That building's name has been changed twice since it was built in 1973.

The Sears Tower was opened in 1973 and is 1,729 feet tall, including its antenna. It was originally named for retailer Sears, Roebuck & Co., which moved its headquarters to Hoffman Estates, Ill. in 1992.

--CNN's Rachael Shackelford contributed to this report.