NSTAR was a utility company that provided retail electricity and natural gas to 1.4 million customers in eastern and central Massachusetts, including the Boston urban area. NSTAR became a subsidiary of Northeast Utilities in April 2012. In February 2015, Northeast Utilities and all of its operating companies became one large company known as Eversource Energy.
NSTAR was formed in 1999 by the merger of BEC Energy and Commonwealth Energy System and had the following operating units: Boston Edison Company, Cambridge Electric Light Company, Commonwealth Electric Company, and NSTAR Gas Company.
As a part of deregulation of the local electrical power industry, NSTAR has divested itself of all electric generation facilities, keeping only those elements of the business which remain regulated. NSTAR sold its interest in the Seabrook Station nuclear power plant to FPL Group in 2002.
On November 16, 2006, the company announced a 7.4% increase in its dividend to an annual rate of USD1.30 per common share from the previous USD1.21.
NSTAR has ownership of unregulated district energy and telecommunications businesses, including Medical Area Total Energy Plant, LLC. which produces electricity, steam and chilled water for sale to customers in the Longwood Medical Area of Boston.
Electric power distribution in the New England area is coordinated by ISO New England, a regional transmission organization.