Constellation Energy trades on Nasdaq under CEG and operates the largest nuclear fleet in the United States. If you are researching CEG stock, you are looking at a competitive power producer rather than a regulated utility. It holds ownership interests in 14 nuclear generating stations covering 25 units, roughly 22 GW, which produced 183 TWh of zero-emissions electricity during 2025 according to the 2025 Form 10-K.
How the Reactor Fleet Becomes Revenue
Constellation does not earn a regulated return. It sells generation into wholesale markets and directly to end customers, so results track power prices and contract terms.
Owned generating resources totalled 31,676 MW at the end of 2025, with a further 4,798 MW procured under unit-specific contracted agreements. The company reports five segments split by geography, led by the Mid-Atlantic at 10,386 MW.
The fleet ran at a 94.7 percent nuclear capacity factor in 2025, which the 10-K describes as roughly four percentage points above the industry average every year since 2013.
On the sales side it served about 204 TWh in 2025 across roughly 2 million customer accounts, including three-fourths of the Fortune 100 and about 1.4 million residential customers. That mix of always-on output and corporate buyers is why it keeps appearing near the top of any nuclear energy stocks screen.
The business also stopped being nuclear-only in January 2026, when the Calpine acquisition closed and brought a large gas and geothermal fleet along with about $12.6 billion of assumed debt.
Video: AP Archive
The Two Data-Center Agreements With Counterparties Named
In September 2024 Constellation executed a 20-year power purchase agreement with Microsoft to support restarting Three Mile Island Unit 1, retired in 2019 for economic reasons and renamed the Crane Clean Energy Center. Microsoft buys the energy, capacity and emissions-free attributes to serve its PJM data centers. The site carries approximately 835 MW of emissions-free capacity once operational.
The second deal covers an existing plant. In June 2025 the company signed a 20-year PPA with Meta Platforms for the output of the Clinton Clean Energy Center, with deliveries beginning in June 2027, supporting relicensing and another two decades of operation.
Both contracts sell electrons from reactors that already exist or already have a licence history. That is the structural difference from a developer such as Oklo, whose revenue depends on building something first, and from the wider small modular reactor field still working through design certification.
What Crane Still Needs Before It Delivers
The restart is not a purely commercial decision. Per the Q2 2026 Form 10-Q, delivery under the Microsoft PPA depends on the NRC comprehensive safety and environmental review plus permits from state and local agencies.
Grid access is the other gate. PJM’s Phase I System Impact Study for Crane flagged contingent transmission upgrades, some with projected in-service dates running as late as December 2030, before the plant is fully deliverable.
Constellation filed a waiver request with FERC in March 2026 to move capacity interconnection rights from the Eddystone units to Crane and shrink that upgrade list. FERC granted the waiver in June 2026.
Financing got separate federal support. The DOE Office of Energy Dominance Financing issued a guarantee for up to $1.0 billion as an unsecured loan toward the restart in November 2025.
Constellation Against Vistra on Reactor Count
Vistra is the closest listed comparison, since it also owns reactors and sells into competitive markets. The gap in fleet size is wide.
| Measure | Constellation Energy (CEG) | Vistra (VST) |
|---|---|---|
| Nuclear units owned | 25 units | 6 units |
| Nuclear sites | 14 generating stations | 4 facilities |
| Nuclear capacity | Approximately 22 GW | 6,448 MW |
| Exchange listing | Nasdaq | NYSE |
| Fiscal year end | December 31 | December 31 |
Constellation figures come from its 2025 Form 10-K and Vistra’s from the Vistra 2025 Form 10-K, which lists six units at four facilities totalling 6,448 MW. Exchange and fiscal year data come from each company’s SEC filer record.
Two dated items decide how the nuclear thesis plays out from here: NRC sign-off on Crane, and whether Clinton deliveries to Meta start on schedule in June 2027. This is general information about a company, not investment advice.
FAQ: CEG Stock
Is CEG stock a utility stock?
Not in the regulated sense. Constellation sells its output into wholesale markets and to retail customers under competitive contracts, so earnings follow power prices and signed agreements rather than a rate case approved by a state commission. Its filings describe it as a competitive generation company.
How much of Constellation’s electricity comes from nuclear?
Nuclear supplied 182,690 GWh of the 204,944 GWh of owned electric supply reported for 2025 in the 10-K, so close to nine tenths of the total. The remainder came from natural gas, oil, hydro, wind and solar assets held across its five reporting segments.
When does the Crane Clean Energy Center restart?
Constellation’s filings tie the date to approvals rather than a fixed calendar target. The NRC review, state and local permits and PJM transmission upgrades all have to land first, and the Q2 2026 10-Q noted contingent upgrades with projected in-service dates running as late as December 2030.
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