Constellation Energy has announced the acquisition of Calpine Corp. in a cash and equity transaction valued at $16.4 billion, which is set to establish the largest producer of clean and reliable energy in the U.S., combining Constellation’s nuclear fleet with Calpine’s natural gas and geothermal operations.

The agreement comprises 50 million Constellation shares and $4.5 billion in cash, in addition to the assumption of $12.7 billion in Calpine net debt. The net acquisition cost is $26.6 billion, reflecting a 7.9x 2026 EV/EBITDA multiple.

The combined entity will have nearly 60 gigawatts of capacity from zero- and low-emission sources across the U.S., Canada, and Mexico, becoming the nation’s leading competitive retail electric supplier serving 2.5 million customers.

The transaction is expected to close within 12 months and will be immediately accretive, with over 20% adjusted EPS accretion in 2026 and adding more than $2 billion in annual free cash flow. Calpine’s significant shareholders, led by Energy Capital Partners, have agreed to an 18-month lock-up period for their Constellation stock ownership.

This is a bold step for Constellation, which has solidified its position as a significant competitive generator since its 2022 separation from its parent company, Exelon. Today, the company possesses the nation’s largest nuclear fleet, which is comprised of 21 GW from 23 units and provides baseload zero-emission power.

“Both companies have been at the forefront of America’s transition to cleaner, more reliable and secure energy, and those shared values will guide us as we pursue investments in new and existing clean technologies to meet rising demand,” said Joe Dominguez, president and CEO, Constellation.