Canadian utility agrees to buy Washington Gas

WGL Holdings, which supplies natural gas to 1.1 million customers in the Washington region, was bought by Calgary-based ­AltaGas in a cash deal worth $6.4 billion, the companies said Wednesday. They hope to close the sale by year’s end.  AltaGas Ltd. said it will relocate its U.S. power business to WGL Holding’s headquarters on Constitution Avenue in Washington. The Canadian firm may add about 20 positions over the next two years, according to executives on both sides of the deal.