Xcel Energy Inc. is a public utility holding company. The Company's operations include the activity of four utility subsidiaries that serve electric and natural gas customers in eight states. The Company's segments include regulated electric utility, regulated natural gas utility and all other. The Company's utility subsidiaries include NSP-Minnesota, NSP-Wisconsin, Public Service Company of Colorado (PSCo) and Southwestern Public Service Co. (SPS), which serve customers in portions of Colorado, Michigan, Minnesota, New Mexico, North Dakota, South Dakota, Texas and Wisconsin. Along with WYCO Development LLC (WYCO), a joint venture formed with Colorado Interstate Gas Company, LLC (CIG) to develop and lease natural gas pipelines storage and compression facilities, and WestGas InterState, Inc. (WGI), an interstate natural gas pipeline company, these companies comprise the regulated utility operations.