Bank One Corporation was the sixth-largest bank in the United States. It traded on the New York Stock Exchange under the stock symbol ONE. The company merged with JPMorgan Chase & Co. on July 1, 2004. The company had its headquarters in the Bank One Plaza in the Chicago Loop in Chicago, Illinois, now the headquarters of Chase's retail banking division.
The bank traces its roots to the Ohio-based First Banc Group, that was formed in 1968 as a holding company for the City National Bank in Columbus, Ohio. Banc One merged with First Chicago NBD to form Bank One in 1998.