FirstEnergy Corp. is a holding company. The Company operates through three segments: Regulated Distribution, Regulated Transmission and Competitive Energy Services (CES). The Regulated Distribution segment distributes electricity through its 10 utility operating companies, serving customers within 65,000 square miles of Ohio, Pennsylvania, West Virginia, Maryland, New Jersey and New York. The Regulated Transmission segment transmits electricity through transmission facilities. The CES segment supplies electricity to end-use customers through retail and wholesale arrangements, including retail sales to customers in Ohio, Pennsylvania, Illinois, Michigan, New Jersey and Maryland. The Company's principal subsidiaries include Ohio Edison Company, The Cleveland Electric Illuminating Company, The Toledo Edison Company, Metropolitan Edison Company, Pennsylvania Electric Company, FirstEnergy Service Company, FirstEnergy Solutions Corp., Allegheny Energy Supply Company, LLC, among others.