Ameren Corporation (Ameren) is a public utility holding company. Ameren's primary assets are its equity interests in its subsidiaries, including Union Electric Company (doing business as Ameren Missouri) and Ameren Illinois Company (Ameren Illinois). Ameren operates through two segments: Ameren Missouri and Ameren Illinois. Ameren Missouri and Ameren Illinois each have one segment. The Ameren Missouri segment for both Ameren and Ameren Missouri includes all the operations of Ameren Missouri. The Ameren Illinois segment for both Ameren and Ameren Illinois consists of all of the operations of Ameren Illinois. Ameren's subsidiaries are separate, independent legal entities with separate businesses, assets, and liabilities. Ameren Missouri operates an electric generation, transmission, and distribution business and a natural gas transmission and distribution business in Missouri. Ameren Illinois operates an electric and natural gas transmission and distribution businesses in Illinois.