---
title: "Constellation Energy → Calpine"
url: "https://mahouse.world/ma-deals/constellation-energy-buy-calpine-2025"
type: "M&A deal"
year: "2025"
---

# Constellation Energy → Calpine

The largest US nuclear operator paid a net $26.6bn including debt for Calpine, the biggest US gas and geothermal generator, creating the largest US power producer as electricity demand from data centres surged — and clearing antitrust review only by selling six plants.

$4.5bn cash plus about 50 million shares and $12.7bn of assumed net debt, with six plant divestitures in Delaware, Pennsylvania and Texas to settle DoJ concerns.

- **Acquirer:** Constellation Energy (United States)
- **Target:** Calpine (United States)
- **Value:** $26.6B
- **Announced:** January 2025
- **Completed:** January 2026
- **Sector:** Energy
- **Deal type:** acquisition

## Why it mattered

Constellation, split from Exelon in 2022, owns the largest US nuclear fleet and in September 2024 had agreed with Microsoft to restart a reactor at Three Mile Island. Calpine brought what nuclear cannot: flexible gas-fired plants from Texas and California to the mid-Atlantic, most of the Geysers geothermal field and a retail business — more than 27,000 megawatts in all. It had been taken private in 2018 by a consortium led by Energy Capital Partners.

The agreement of 10 January 2025 valued Calpine's equity at about $16.4bn — 50 million Constellation shares and $4.5bn in cash — plus about $12.7bn of net debt. After the cash Calpine would generate before closing and its tax attributes, Constellation put the net price at $26.6bn, 7.9 times expected 2026 EBITDA. State regulators and the Federal Energy Regulatory Commission approved by July 2025.

The review that mattered was the Justice Department's. On 5 December 2025 it sued to block the deal and at the same time filed a settlement, joined by Texas, requiring the sale of six plants in Delaware, Pennsylvania and Texas. Without them, it said, the combination would be the largest US wholesale generator, able to profit from withholding output in the PJM and ERCOT markets. It was the division's first consent decree in an electricity merger in 14 years. The deal completed on 7 January 2026.

## What it left behind

Most of the equity was paid in shares, and Constellation's had risen: the consideration recorded at completion was about $21.8bn rather than $16.4bn, with $11.1bn of goodwill. Calpine's minority stake in the Gregory plant was sold in January 2026; in March five PJM plants with about 4.4 gigawatts were agreed for sale to LS Power for $5.0bn, and in August the Brazos Valley plant in Texas, formerly the Jack A. Fusco Energy Center, followed for $860m, both sales due to close by the end of 2026. Calpine, now a Constellation business with about 23 gigawatts, signed a 380-megawatt agreement to supply a CyrusOne data centre beside its Freestone plant in Texas.

Paying mostly in stock let Constellation fund a $26.6bn deal with $4.5bn of cash; the real cost was set on closing day, when the 50 million shares were worth almost half as much again as at signing.

Source: https://www.justice.gov/opa/pr/justice-department-requires-divestitures-proceed-constellations-proposed-266-billion