Eversource Energy is a publicly traded, Fortune 500 energy company headquartered in Springfield, Massachusetts with additional corporate offices in Hartford, Connecticut, and Boston, Massachusetts, with several regulated subsidiaries offering retail electricity, natural gas service and water service to approximately 4 million customers in Connecticut, Massachusetts, and New Hampshire. Following its 2012 merger with Boston-based NSTAR, Northeast Utilities had more than 4,270 circuit miles of electric transmission lines, 72,000 pole miles of distribution lines, and 6,459 miles of natural gas pipeline in New England. Through predecessors New England Gas & Electric System and Commonwealth Energy Systems, Eversource is the direct legal successor of the Associated Gas & Electric System, a labyrinthine trust corporation based in Massachusetts controlling over a hundred regional gas, electric, railroad and other utility monopolies across the United States, and as distant as Manila. On February 2, 2015, this company and all its subsidiaries rebranded themselves as "Eversource Energy". The stock symbol changed on February 19, 2015, from "NU" to "ES". Wikipedia