Vistra is a holding company. Through its subsidiaries, Co. is operating an integrated retail and electric power generation business throughout the U.S. Co. has six segments: Retail, which is engaged in retail sales of electricity and natural gas; Texas and East, which are engaged in electricity generation, wholesale energy sales and purchases, commodity risk management activities, fuel production and fuel logistics management; West, which represents results from the California Independent System Operator market; Sunset, which consists of generation plants with announced retirement plans; and Asset Closure, which is engaged in the decommissioning and reclamation of retired plants and mines.