MGE Energy, Inc., through its subsidiaries, operates as a public utility holding company in Wisconsin. The company's Regulated Electric Utility Operations segment engages in generating, purchasing, and distributing electricity. Its Regulated Gas Utility Operations segment is involved in purchasing and distributing natural gas. The company's Nonregulated Energy Operations segment engages in constructing, owning, and leasing electric generating capacity. Its Transmission Investments segment invests in American Transmission Company LLC, which provides electric transmission services primarily in Wisconsin. The company generates electricity from coal, natural gas, fuel oil, and wind, as well as purchases power under short and long-term commitments. It owns gas fired combustion turbines that have a total of 155 megawatt (MW) net summer rated capacity; 30 MW consisting of 18 turbines in a wind-powered electric generating facility; and 11 MW consisting of 17 turbines in a wind-powered electric generating facility. The company primarily serves residential, commercial, and industrial customers, as well as public authorities, other utilities, and power marketers. As of December 31, 2012, it supplied electricity to approximately 140,000 customers in the cities of Fitchburg, Madison, Middleton, and Monona; and natural gas to approximately 145,000 customers in the cities of Elroy, Fitchburg, Lodi, Madison, Middleton, Monona, Prairie du Chien, Verona, and Viroqua. MGE Energy, Inc. was founded in 1855 and is based in Madison, Wisconsin.