Chicago's city center faces huge office vacancies, ownership changes and new competitors

CHICAGO - Corporate moves from the suburbs, record tourism and booming real estate development are fueling downtown Chicago's economy, but the good times have produced one big unexpected challenge.

Office owners are staring down a wave of upcoming large vacancies that could alter how the city's core works in the decades to come.

Part of the problem is due to changing tenant preferences, competition from sparkling new skyscrapers along the Chicago River and the emergence of entirely new office markets such as the Fulton Market district.

At the same time, an unusually large number of office towers on and around the LaSalle Street canyon - for decades the center of Chicago's financial sector - are up for sale. Among properties that could change hands are the James R. Thompson Center and the Chicago Board of Trade Building.

The future could rest in the hands of new building owners and their efforts to stem the exodus from the Central Loop.