Exelon Corp. operates as a utility services holding company, which engages in the energy generation, power marketing, and energy delivery business. The company operates through the following segments: ComEd, PECO, BGE, Generation's Mid Atlantic, Midwest, New England, New York, ERCOT and other regions in Generation. The ComEd segment engages in energy delivery business, which consists of the purchase and regulated retail sale of electricity and the provision of electricity transmission and distribution services to retail customers in northern Illinois, including the city of Chicago. The PEC segment engages in energy delivery business, which consists of the purchase and regulated retail sale of electricity and the provision of electricity transmission and distribution services to retail customers in southeastern Pennsylvania, including the city of Philadelphia, as well as the purchase and regulated retail sale of natural gas and the provision of natural gas distribution services to retai