Xcel Energy Inc. is a public utility holding company. The Company's operations include the activity of four wholly owned utility subsidiaries that serve electric and natural gas customers in eight states. These utility subsidiaries are NSP-Minnesota NSP-Wisconsin, Public Service Company of Colorado (PSCo) and Southwestern Public Service Co. (SPS) and serve customers in portions of Colorado, Michigan, Minnesota, New Mexico, North Dakota, South Dakota, Texas and Wisconsin. Its segments include regulated electric utility, regulated natural gas utility and all other. The regulated electric utility segment generates, transmits and distributes electricity in Minnesota, Wisconsin, Michigan, North Dakota, South Dakota, Colorado, Texas and New Mexico. Regulated electric utility also includes commodity trading operations. The regulated natural gas utility segment transports, stores and distributes natural gas primarily in portions of Minnesota, Wisconsin, North Dakota, Michigan and Colorado.