Sources close to the deal say Mortimer Zuckerman's Boston Properties Inc. recently dropped out of the bidding, but the privately held Shorenstein Co., which owns 50% of the center, remains confident of the sale and the price.

According to investment analysts, if the BofA Center sells for $1 billion, Shorenstein could take a $500 million cut, giving the real estate investment firm a 33% return on its original $660 million investment. The other 50% interest in the property belongs to Charlotte's NationsBank, which acquired Bank of America in 1998.

The Bank of America Center occupies a corner of downtown on California and Montgomery streets. The Center is comprised of three buildings including 555 California St., a 1.5-million-sf class A office building.