The Union Electric Company of Missouri (formerly NYSE: UEP) was an electric power utility that was organized in 1902 and grew to be one of the large U.S. companies listed among the S&P 500. In 1997, its holding company merged with a smaller neighboring utility, Central Illinois Public Service Company through its holding company, CIPSCO Inc. (formerly NYSE: CIP), to form Ameren Corporation (NYSE: AEE) based in St. Louis, Missouri.[1]