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.

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.

Separately, Calpine and Constellation are already among the largest power generation companies in the country.