Duke Energy Corp. will buy Progress Energy Inc. for $13.7 billion, creating a company that will surpass Southern Co. as the largest U.S. utility.

"Duke, based in Charlotte, North Carolina, will assume about $12.2 billion in Progress Energy’s debt. A deal for Progress would add units that operate near Duke’s service territories inNorth Carolina and South Carolina, as well as an electric distribution unit in Florida. Progress also owns more than 22,000 megawatts of power generation capacity, according to its website."