Constellation Energy
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Constellation Energy (Nasdaq: CEG) is an American power producer headquartered in Baltimore, Maryland, and the largest operator of nuclear power plants in the United States. The company was created on February 1, 2022, when Exelon spun off its competitive generation and retail business into a separate public company, leaving Exelon as a pure regulated utility. Constellation runs the nation's biggest fleet of nuclear power reactors, sells electricity and natural gas to roughly two and a half million homes and businesses, and has become the central counterparty in the rush to power AI data centers with around-the-clock carbon-free electricity. Its September 2024 agreement to restart Three Mile Island Unit 1 for Microsoft, and its January 2025 deal to buy Calpine, turned the company into a primary lens through which investors view the link between nuclear power and the artificial-intelligence buildout. Because hyperscale computing needs firm, 24/7 power and nuclear plants are among the few large carbon-free sources that can supply it, Constellation's reactors have become a binding input to AI infrastructure rather than a commodity.
Constellation traces its corporate roots to Baltimore Gas and Electric and to the old Constellation Energy Group, which merged with Exelon in 2012. For a decade the nuclear and competitive-generation assets sat inside Exelon. On January 20, 2022, Exelon set the record date for a tax-free separation, and the distribution took effect at 12:01 a.m. Eastern Time on February 1, 2022. Exelon shareholders received one share of Constellation common stock for every three Exelon shares they held, with cash paid in lieu of fractional shares. Constellation began trading as an independent company on the Nasdaq under the ticker CEG, describing itself at launch as the largest producer of carbon-free energy in the United States, supplying about 10 percent of the country's emissions-free electricity.
The company is led by president and chief executive Joseph Dominguez, a former federal prosecutor and longtime Exelon executive. Under Dominguez, Constellation has pursued a strategy of extending the operating lives of its reactors, increasing their output through equipment upgrades known as uprates, and signing long-term contracts that lock in premium prices from technology companies and the federal government.
Constellation owns and operates the largest nuclear fleet in the United States: about 21 operating reactors across 12 sites, with total generating capacity of roughly 22,000 megawatts (about 22 gigawatts). That is close to a quarter of all U.S. nuclear capacity. In 2025 the fleet ran at a capacity factor of 94.7 percent and produced approximately 182 million megawatt-hours of electricity, a level of reliability that is central to the company's appeal to data-center customers. Most of the reactors sit in Illinois, with additional sites in Maryland, New York, and Pennsylvania, plus minority interests in plants in New Jersey and Texas.
| Plant (site) | State | Reactors | Notes |
|---|---|---|---|
| Braidwood | Illinois | 2 | PWR |
| Byron | Illinois | 2 | PWR |
| LaSalle | Illinois | 2 | BWR |
| Dresden | Illinois | 2 | BWR |
| Quad Cities | Illinois | 2 | BWR |
| Clinton | Illinois | 1 | BWR; full output contracted to Meta |
| Calvert Cliffs | Maryland | 2 | PWR |
| Nine Mile Point | New York | 2 | BWR |
| Ginna | New York | 1 | PWR |
| FitzPatrick | New York | 1 | BWR |
| Limerick | Pennsylvania | 2 | BWR |
| Peach Bottom | Pennsylvania | 2 | BWR (co-owned) |
| Salem | New Jersey | minority interest | operated by PSEG |
| South Texas Project | Texas | minority interest | |
| Crane (Three Mile Island Unit 1) | Pennsylvania | 1 | retired 2019; restart targeted 2027 |
On September 20, 2024, Constellation announced a 20-year power purchase agreement with Microsoft that would fund the restart of Three Mile Island Unit 1, a reactor the company had shut in 2019 for economic reasons. The deal was, at the time, the largest power purchase agreement Constellation had ever signed, and it was the first time a previously retired U.S. commercial reactor was slated to be brought back specifically to serve a corporate buyer. Microsoft agreed to take the plant's full output, roughly 835 megawatts of carbon-free electricity, to match the growing power consumption of its data centers in the PJM region.
Constellation renamed the facility the Crane Clean Energy Center, after Chris Crane, the former Exelon and Constellation nuclear executive who died in April 2024. The company expects to invest about $1.6 billion to refurbish and restart the unit, a cost of roughly $1,900 per kilowatt that is a small fraction of new-build nuclear economics. The restart was originally targeted for 2028 but was accelerated to 2027 after PJM granted expedited interconnection approval; by September 2025 the site was about 80 percent staffed, with around 500 full-time employees. Constellation also plans to seek a license extension to operate the plant to at least 2054. The project received a $1 billion loan from the U.S. Department of Energy, which closed on November 18, 2025, under the Trump administration's push to expand nuclear output.
An important distinction: the reactor being restarted is Unit 1, which operated safely and independently from Unit 2. Unit 2 is the reactor that suffered a partial meltdown in 1979, the most serious accident in U.S. commercial nuclear history; it has been permanently closed since then and is owned by a separate company (EnergySolutions subsidiary TMI-2 Solutions) that is decommissioning it. The Crane restart does not involve Unit 2 in any way. Restart of Unit 1 still requires approval from the Nuclear Regulatory Commission, which is reviewing the plant under a dedicated restart panel.
The Microsoft agreement was the first of a series of large contracts tied to AI-driven electricity demand. On June 3, 2025, Constellation signed a 20-year deal with Meta for the full output of its Clinton Clean Energy Center in Illinois, about 1,121 megawatts, with deliveries beginning in June 2027. The contract is a market-based replacement for Illinois's expiring zero-emission credit subsidy, preserves roughly 1,100 jobs, supports relicensing the plant for another two decades, and funds a 30-megawatt uprate. In 2025 Constellation also won what it called the largest energy procurement in the history of the U.S. General Services Administration: a 10-year, $840 million contract to supply more than a million megawatt-hours of nuclear power a year to more than a dozen federal agencies, partly from planned uprates. In early 2026 the company added a 380-megawatt supply agreement with data-center developer CyrusOne in Texas and entered roughly 5 gigawatts of new nuclear-uprate, gas, and battery capacity into the PJM interconnection queue.
| Counterparty | Asset | Capacity | Term | Start | Announced |
|---|---|---|---|---|---|
| Microsoft | Crane (Three Mile Island Unit 1) | ~835 MW | 20 years | 2027 (target) | Sep 20, 2024 |
| Meta | Clinton Clean Energy Center | ~1,121 MW | 20 years | Jun 2027 | Jun 3, 2025 |
| U.S. General Services Administration | fleet nuclear | >1M MWh/yr | 10 years | 2025 | 2025 |
| CyrusOne | Texas data center | 380 MW | n/d | n/d | early 2026 |
On January 10, 2025, Constellation agreed to acquire Calpine Corporation, the largest U.S. generator of electricity from natural gas and the largest operator of geothermal capacity in the country through its Geysers complex in California. The equity purchase price was about $16.4 billion, made up of 50 million Constellation shares plus $4.5 billion in cash, and the deal carried roughly $12.7 billion of assumed Calpine net debt, for a total transaction value of approximately $26.6 billion. Constellation framed the acquisition as the creation of the nation's largest producer of clean and reliable energy and a major expansion into Texas, the fastest-growing U.S. power market.
The transaction closed on January 7, 2026, after the Department of Justice required the divestiture of six power plants to resolve antitrust concerns. The combined company has about 55 gigawatts of generating capacity spanning nuclear, natural gas, geothermal, hydro, wind, solar, and battery storage, and serves roughly 2.5 million retail and commercial customers across markets including Texas, California, Illinois, Maryland, New York, and Pennsylvania. Calpine added about 23 gigawatts of mostly gas-fired generation. Management said the deal would add roughly $2 billion in annual free cash flow, and on closing Constellation raised its dividend by about 10 percent. The acquisition gave Constellation a portfolio of dispatchable gas plants to pair with its nuclear baseload, useful for serving data centers that need both firm capacity and the ability to ramp.
A central regulatory question for Constellation and its peers is how data centers should connect to power plants. In a "co-location" or "behind-the-meter" arrangement, a data center plugs directly into a generator and draws power without flowing it across the public transmission grid, which can let the load avoid some grid charges. This model became contentious in November 2024, when FERC rejected an amended interconnection agreement that would have let Talen Energy expand a behind-the-meter sale from its Susquehanna nuclear plant to an Amazon Web Services data center, freezing a wave of similar deals across PJM. Days later, on November 22, 2024, Constellation filed its own complaint at FERC arguing that PJM's tariff was unjust because it lacked rules for what Constellation called "fully isolated co-located load."
The Microsoft and Meta deals are structured differently from the Talen arrangement: Constellation sells the reactors' output to the grid while the technology buyer purchases a matching quantity of carbon-free power, a front-of-the-meter contract that sidestepped the co-location dispute. The broader fight continued at FERC. On December 18, 2025, the commission ordered PJM to create new rules for co-locating large loads at power plants, directing the grid operator to establish several new transmission services and to revise its behind-the-meter generation rules within 60 days. Analysts described the order as a victory for plant owners such as Constellation, Vistra, and Public Service Enterprise Group. Even so, Constellation said in early 2026 that some data-center customers had paused contract talks pending final clarity on PJM's co-location and capacity-auction rules.
Constellation reports a volatile GAAP bottom line because of non-cash mark-to-market accounting on its hedging contracts, so management guides to "adjusted operating earnings." For full-year 2025, reported on February 24, 2026, the company posted GAAP net income of $7.40 per share and adjusted operating earnings of $9.39 per share on revenue of about $25.5 billion, up roughly 8 percent year over year. GAAP earnings were lower than 2024's unusually high $11.90 per share, a swing driven mainly by mark-to-market effects rather than operations. After closing the Calpine deal, Constellation set full-year 2026 adjusted operating earnings guidance of $11.00 to $12.00 per share. First-quarter 2026 results, the first to include Calpine, showed revenue of about $11.1 billion, GAAP net income of $4.49 per share, and adjusted operating earnings of $2.74 per share, up 44 percent from a year earlier.
| Metric | Q4 2025 | FY 2025 | Q1 2026 | FY 2026 guidance |
|---|---|---|---|---|
| Revenue | n/d | ~$25.5 billion | ~$11.1 billion | not disclosed |
| GAAP net income per share | $1.38 | $7.40 | $4.49 | n/a |
| Adjusted operating earnings per share | $2.30 | $9.39 | $2.74 | $11.00 to $12.00 |
| Nuclear capacity factor | n/d | 94.7% | n/d | n/a |
Training and serving large AI models requires enormous, steady electricity, and the constraint on building new data centers has shifted from chips to power. Nuclear plants are attractive to hyperscalers because each reactor delivers hundreds of megawatts of firm, carbon-free output that runs around the clock, matching the constant load of a data center far better than intermittent wind or solar. Constellation owns more of that capacity than any other U.S. company, which is why Microsoft, Meta, and others have signed multi-decade contracts with it rather than waiting for new generation to be built. The company's strategy of restarting Crane, relicensing and uprating existing reactors, and using Calpine's gas fleet for additional firm capacity positions it as a key supplier to the AI buildout. The same demand has revived interest in small modular reactors and developers such as Oklo, but those technologies remain years from large-scale deployment, leaving Constellation's existing reactors as some of the only near-term carbon-free firm power available at gigawatt scale.
| Date | Event |
|---|---|
| Feb 1, 2022 | Separation from Exelon completed; Constellation begins trading as CEG |
| Sep 20, 2024 | 20-year Microsoft PPA to restart Three Mile Island Unit 1 (Crane Clean Energy Center) announced |
| Nov 22, 2024 | Constellation files FERC complaint against PJM over co-located load rules |
| Jan 10, 2025 | $16.4 billion agreement to acquire Calpine announced |
| Jun 3, 2025 | 20-year Meta PPA for Clinton Clean Energy Center (1,121 MW) signed |
| Nov 18, 2025 | $1 billion Department of Energy loan for Crane restart closes |
| Dec 18, 2025 | FERC orders PJM to create co-location rules for data centers |
| Jan 7, 2026 | Calpine acquisition closes; combined fleet about 55 GW |
| Feb 24, 2026 | Full-year 2025 results; 2026 guidance of $11.00 to $12.00 per share |