BOK Financial Corporation — pronounced as letters, "B-O-K" — is a financial services holding company headquartered in Tulsa, Oklahoma. Offering a full complement of retail and commercial banking products and services across the American Midwest and Southwest, the company is one of the 50 largest financial services firms in the U.S., and the largest in Oklahoma.

Tulsa is the second-most-populous city in the state of Oklahoma, after Oklahoma City, and is the 47th-most-populous city in the United States. The population was 413,066 as of the 2020 census. It is the principal municipality of the Tulsa metropolitan area, a region with 1,034,123 residents. The city serves as the county seat of Tulsa County, the most densely populated county in Oklahoma, with urban development extending into Osage, Rogers and Wagoner counties.