ONEOK Inc. is a diverse corporation headquartered in Tulsa, Oklahoma. They are engaged in the marketing of natural gas. The company operating through its subsidiary Oklahoma Natural Gas Company serves more than three quarters of Oklahoma and, in terms of customers served, it is the twentieth-largest gas company in the United States of America.
Putting ONG Transmission Company, another subsidiary, to good use ONEOK leases pipelines and uses those pipelines as a vital link in their interstate gas transport venture. Its non-utility division, The Energy Companies, is a crucial natural gas as well as liquids processor and a moderate sized gas and oil exploration company.