BOK Financial Corporation is a bank holding company headquartered in the BOK Tower in Tulsa, Oklahoma. The company is 60% 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. As of December 17, 2017, 17% 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, BOK Financial Securities and the Milestone Group.