More than half a million homes and businesses across seven states were left without power after a winter storm swept across parts of the U.S. Northeast on Sunday and Monday. Massachusetts-based Eversource Energy (NYSE:ES) was the hardest-hit utility after 135,797 of its 3.3 million customers were left in the dark, while Ohio’s FirstEnergy Corp. (NYSE:FE) saw 81,257 of its 6.2 million U.S. customers affected. A massive historic winter storm is currently lashing the U.S. Northeast and Mid-Atlantic. The storm has triggered blizzard warnings…