Osborn spoke of the company's plans last week after his annual shareholder meeting, the Chicago Tribune reported Saturday.
Northern Trust is one of the last large publicly traded financial companies in the Chicago area. Despite's Northern's present plans, it may be forced to join with another financial institution, said Kenneth Lewis, chairman and chief executive of Bank of America Corp.
"I haven't looked at Northern Trust in quite some time, and I don't know how big they are anymore," Lewis said. "But I'd doubt that five years from now that they'd be independent."
Lewis was in Chicago last week to meet with bank employees and Chicago officials about Bank of America's proposed $21 billion purchase of LaSalle Bank.