Dynegy is buying 10 power plants and a retail sales company owned by Duke Energy Corp. for $2.8 billion, and another nine power plants through a $2.45 billion purchase of Duke shares owned by private equity firm Energy Capital Partners. Dynegy will issue $5 billion in debt and sell $1.2 billion in stock.

Once the acquisition closes in Q1 2015, Dynegy will generate 26,000 megawatts of power, enough to supply nearly 21 million U.S. homes, making it the United States’ second-largest independent power producer along with Calpine Corp. The largest independent power producer is NRG Energy at 52,466 megawatts.

Independent power producers do not own regulated utilities, and they operate independently from the regulatory price schedules that apply to regulated utilities. IPPs sell their power to regulated utilities and other end users, but the power generated by IPPs is subject to market pricing, which just three years ago forced Dynegy to fil