MGE Energy, Inc., through its subsidiaries, operates as a public utility holding company primarily in Wisconsin. It operates through Regulated Electric Utility Operations; Regulated Gas Utility Operations; Nonregulated Energy Operations; Transmission Investments; and All Other. The company generates, purchases, and distributes electricity; owns or leases electric generation facilities located in Wisconsin and Iowa; and plans, constructs, operates, maintains, and expands transmission facilities to provide transmission services.