Constellation Energy agreed to buy Calpine for $16.4 billion, combining two of the country’s largest electricity generators at a time when their product is in high demand from tech companies. Including the assumption of debt,

U.S. nuclear power provider Constellation Energy on Friday agreed to buy privately held natural gas and geothermal company Calpine Corp for $16.4 billion, one of the biggest acquisitions in U.S. power industry history.

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.