Constellation Energy is nearing a roughly $30 billion deal to acquire power producer Calpine, people familiar with the matter said on Wednesday, a move that would significantly expand Constellation's generation assets at a time of rising U.

Constellation is buying power natural gas and geothermal power provider Calpine in a cash-and-stock deal valued at approximately $16.4 billion, joining together two of the country’s biggest power companies.

Constellation Energy Corp. is nearing an acquisition of Calpine Corp., people familiar with the matter said, in what would be one of the biggest ever deals in the power generation sector.

Baltimore-based Constellation’s plans to acquire a Houston, Texas,-based natural gas  producer in a $26.6 billion deal will create one of the nation’s biggest energy firms at a time

Constellation Energy Corporation CEG and Calpine Corp. announced that they have entered into a definitive agreement under which CEG will acquire Calpine in a cash and stock transaction valued at an equity purchase price of nearly $16.