How the company works
What it sells, how it makes money, and the anatomy of the extremes: what has to break for the result to land far from the forecast, either way. In Constellation Energy's own words, from its annual report for 2025.
Constellation makes electricity and sells it. It runs the largest nuclear fleet in the U.S.: 14 nuclear stations with 25 units and approximately 22 GWs of capacity. On January 7, 2026 it bought Calpine, the largest U.S. generator of electricity from natural gas and geothermal resources, which added approximately 23 GWs. The combined fleet holds 55 GWs.
How it makes money
Constellation sells the power its plants make, and power it buys in the market, to wholesale buyers and to retail customers, mostly commercial and industrial companies. It served approximately 204 TWhs in 2025, of which 147 TWhs were retail, and it also sold approximately 800 Bcf of natural gas. It is also paid for keeping plants available, through capacity auctions in every major region except Texas. Operating revenues were $25.5B in 2025, up 8.3% from $23.6B. Net income was $2.32B, $7.40 a share, down from $3.75B, $11.89 a share, mostly because the nuclear production tax credit in revenues fell from $2,080M to $320M and hedges marked at market value lost money.
What it sells
| Operating revenues by region | 2025 | 2024 |
|---|---|---|
| Mid-AtlanticThe eastern half of PJM: New Jersey, Maryland, Virginia, West Virginia, Delaware, the District of Columbia and parts of Pennsylvania and North Carolina. | $6,487M | $5,522M |
| MidwestThe western half of PJM and the U.S. footprint of MISO, except its Southern Region. | $5,804M | $4,805M |
| New YorkOperations within NYISO. | $2,190M | $2,050M |
| ERCOTMost of Texas. ERCOT has no capacity market. | $1,904M | $1,550M |
| Other Power RegionsNew England, the South, the West and Canada. | $5,583M | $5,506M |
| OtherNatural gas sales, other energy products and gains or losses on hedges not allocated to a region. | $3,565M | $4,135M |
Operating revenues by segment as the annual report's segment note prints them; Other includes unrealized hedge losses of $805M in 2025 and gains of $316M in 2024.
Unit economics
The company judges each region by revenue less purchased power and fuel. That margin was $10.9B in 2025, against $12.1B in 2024: revenues of $25.5B less $14.7B of purchased power and fuel. A nuclear plant has a high fixed cost and a low cost for each extra MWh, so output matters: the fleet ran at a 94.7% capacity factor, and nuclear made 68% of the company's total electric supply. Operating and maintenance cost $6.16B. Operating activities provided $4.24B of cash, and capital expenditures were $2.95B.
Competitive position
Constellation operates the largest fleet of plants that emit no carbon in the U.S., and its nuclear capacity factor has been approximately four percentage points better than the industry average each year since 2013. Data centers want power around the clock, and it has a 20-year agreement with Microsoft to buy the output of the Crane Clean Energy Center, formerly Three Mile Island Unit 1, once the plant restarts with approximately 835 MWs. Calpine adds 21 GWs of natural gas plants, mostly in Texas, California and the Northeast, the Geysers geothermal plants of approximately 730 MWs and approximately 62 TWhs of retail load. It competes in open wholesale and retail markets, where prices are set by supply and demand.
Biggest cost inputs
Purchased power and fuel: $14.7B in 2025, up from $11.4B. Operating and maintenance: $6.16B. Nuclear fuel, from a supply chain that sanctions on Russian uranium affect. Depreciation and amortization: $985M. A workforce of 15,339 employees at the end of 2025, approximately 23% of them under collective bargaining agreements, plus approximately 2,500 who joined with Calpine.
Anatomy of a large upside
- Capacity prices and data-center demand stay high. The average capacity price in the Mid-Atlantic region rose 246.5% in 2025, to $179.79 a MW-day. Demand for power from data centers is rising, and long contracts such as the Crane agreement with Microsoft lock in the price of output for many years.
- Calpine earns more than planned. Calpine adds approximately 23 GWs of plants, much of it in Texas and California where demand grows fast, and a retail platform that brings new customers and sales channels.
Anatomy of a large downside
- Power prices fall or hedges swing. Revenues move with power prices, and hedges marked at market value took $805M from revenues in 2025. The nuclear production tax credit pays most when power prices are low; it fell from $2,080M to $320M of revenues as prices rose.
- Market rules change. In January 2026 the National Energy Dominance Council and the governors in PJM urged PJM to protect residential customers from capacity price increases. In December 2025 FERC ordered PJM to change its rules for plants that serve data centers on site. The Crane restart still needs regulatory approvals.
Written from Constellation's annual report for the year ended December 31, 2025. Unless the report says otherwise, its figures exclude Calpine, acquired on January 7, 2026. The upside and downside describe conditional business outcomes drawn from that report; the quarter's forecast and its cases are on the forecast pages.