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.

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.

Baltimore's Constellation Energy buying Calpine in a deal that joins two huge U.S. power companies George W. Bush gave fellow former president Barack Obama a friendly belly tap at the Jan. 9 funeral of Jimmy Carter, and the internet was obsessed with the viral moment.