The merged company was originally named MarketSpan Corp , but its name was later changed to retain the KeySpan identity. The remaining assets were acquired by the Long Island Power Authority. KeySpan became a registered holding company upon the acquisition of two gas distribution companies. It has subsidiaries in the coal, gas and oil businesses. Previously, Midwest Power Systems was formed from the 1992 merger of Iowa Public Service Co .
Company has a power marketing subsidiary.
MidAmerican merged with CalEnergy Company, an independent power producer, in 1999, and was acquired by a private investor group headed by Berkshire Hathaway in 2000. Beginning September 2000, the company will do business as Allete . Its power marketing arm is MPEX . Montana Power is an electric utility that has telecommunications, and power marketing subsidiaries as well as subsidiaries that own oil and gas properties. NorthWestern Corp. National Grid USA is a registered holding company that owns Massachusetts Electric , Narragansett Electric , Granite State Electric, Nantucket Electric and New England Power Company .