On January 5, Constellation announced the completion of its acquisition of Calpine Corporation from Energy Capital Partners in a deal valued at $12.6 billion, including the assumption of approximately $11.8 billion in net debt. The transaction creates the largest producer of electricity in the United States, expanding Constellation’s generating capacity by nearly 50 percent and adding Calpine’s 29 gigawatts of natural gas–fired combined-cycle and steam turbine plants to Constellation’s existing portfolio.

In conjunction with closing the deal, Constellation’s subsidiary issued $2.75 billion of senior notes across four tranches. Proceeds will be used to retire Calpine’s outstanding borrowings and refinance existing maturities, lowering the blended cost of debt and extending the average maturity by approximately three years. Credit rating agencies have affirmed Constellation’s investment-grade ratings, citing the balanced approach to leverage and liquidity maintenance.

Following integration, Constellation now operates more than 60 gigawatts of generation capacity, including 22 gigawatts of nuclear, 16 gigawatts of renewables (wind and solar), 10 gigawatts of hydroelectric and nearly 12 gigawatts of natural gas, oil and other thermal assets. The company’s combined nuclear fleet now supplies roughly 10 percent of U.S. carbon-free electricity, while its renewables platforms are positioned to add 5 gigawatts of new wind and solar projects under development over the next three years.

The acquisition broadens Constellation’s geographic footprint across five operating regions—Mid-Atlantic, Midwest, New York, ERCOT and Other Power Regions—serving more than 3 million residential, commercial and municipal customers. Calpine’s customer contracts add long-term power purchase agreements with industrial and data center customers that are set to generate stable cash flows and improve Constellation’s earnings visibility through 2030.