Bank One, aka First USA Bank, spells its banking business as "bank." But, if you get a mortgage loan from Bank One, Bank One sells its mortgagee interest to a mortgage company, presumably held by the same umbrella interest, called "Banc One." They are emphatic about the spelling, since the k/c difference distinguishes two legal entities. I suppose there is another head of the hydra somewhere which calls itself "Banque One."