Phoenix-based, Pinnacle West and its affiliates, provide energy and related products to people and businesses throughout Arizona. The company owns Arizona Public Service Company (APS), an electric utility that provides either retail or wholesale electric service to more than 900,000 customers in 11 of Arizona’s 15 counties. The company's other major subsidiaries include Pinnacle West Energy Corporation, APS Energy Services, SunCor Development Company and El Dorado Investment Company.