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,

Constellation Energy Corp. shares surged to a record high after agreeing to acquire closely held Calpine Corp. for $16.4 billion in a deal that will create the largest fleet of US power stations.Most

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