BOK Financial Corporation is a bank holding company headquartered in the BOK Tower in Tulsa, Oklahoma. The company is more than 50% owned by George Kaiser, who acquired the bank in 1991 from the FDIC. It is the largest bank in Oklahoma, with 14% of the total deposits in the state. Known for its energy roots, as of June 30, 2021, 14% of its loan portfolio was to borrowers in the petroleum industry.
BOK is an acronym for "Bank of Oklahoma." The company's banking subsidiary BOKF, NA operates in 8 states under the brands Bank of Oklahoma, Bank of Texas, Bank of Albuquerque and BOK Financial. It also operates TransFund, Cavanal Hill Investment Management and BOK Financial Securities.