Exelon Corporation
Regulated Electric and Gas UtilitiesFounded 2000- Updated June 2026
Reviewed by Swet Parvadiya
Last reviewed: June 2026
CorpDigest
Exelon Corporation
Company History
Founded 2000 in Chicago, Illinois
Last reviewed: 2026-06-09T00:00:00Z · By Swet Parvadiya
1882: Chicago Edison Company begins supplying electricity to downtown Chicago. 1881: Philadelphia Electric Company starts operations in Pennsylvania. These two utilities operated independently for over a century, building distribution infrastructure across their respective service territories through the industrialization of America, two world wars, and the postwar suburban expansion.
The 2000 merger of PECO Energy and Unicom (parent of Commonwealth Edison) created Exelon Corporation — a combination that brought together the Philadelphia and Chicago utility legacies under a single holding company. The merged entity immediately ranked among the largest utilities in the country by customer count and rate base.
The 2012 spin-off of Constellation Energy was an early signal of the pure-play regulated utility direction, though Constellation at that time retained significant unregulated nuclear generation. The 2016 acquisition of Pepco Holdings — a deal initially blocked by D.C. Regulators before eventually receiving approval — added the Mid-Atlantic service territory and extended the geographic corridor that defines Exelon's footprint.
The complete separation of Constellation in 2022 completed the transformation that the 2012 spin-off had started. The Exelon that remains is a distribution-focused regulated utility with no exposure to commodity power markets — a structure that institutional investors in regulated utilities explicitly prefer.
Exelon Corporation was formed in 2000 through the merger of PECO Energy Company and Commonwealth Edison, establishing a corporate structure that would evolve into the largest pure-play regulated utility in the United States. The merged entity approached the problem of energy distribution with a deep understanding of industrial engineering and commercial strategy, recognizing that the consolidation of the utility sector would create massive opportunities for operational efficiency and regulatory leverage. Its early success was driven by its ability to navigate the complex political and regulatory landscape of the United States, leveraging the technical expertise of its legacy utility workforces to secure access to the vast distribution networks of the Midwest and Mid-Atlantic. The company instilled a culture of long-term strategic planning, technical excellence, and operational discipline, creating a corporate DNA that remains visible in its willingness to invest in massive, long-lead-time grid modernization projects and its deep integration across the utility value chain. Its visionary leadership and unwavering focus on regulatory alignment laid the foundation for two decades of growth and adaptation, transforming a diversified energy conglomerate into a global leader in regulated electricity and natural gas distribution.
The Chicago Edison Company is founded, later evolving into Commonwealth Edison (ComEd) under the leadership of Samuel Insull, establishing the foundation for modern electric utility distribution in the Midwest.
The Philadelphia Electric Company is established to provide reliable power to the rapidly growing industrial hub of Philadelphia, building a dense network of wires and substations that would become the backbone of the region's economy.
PECO Energy Company and Commonwealth Edison execute a landmark, $34 billion merger of equals to form Exelon Corporation, creating a massive, diversified energy conglomerate with significant regulated and competitive assets.
Exelon spins off its competitive power generation business into a separate, publicly traded company named Constellation Energy, allowing Exelon to focus more heavily on its regulated utility operations, though the two would later re-merge briefly before a final split.
Following a lengthy regulatory battle, Exelon successfully completes the $6.8 billion acquisition of Pepco Holdings, instantly expanding its regulated footprint into Washington D.C., Maryland, and Delaware, and solidifying its position as the largest regulated utility in the United States by customer count.
The state of Illinois passes the Future Energy Jobs Act, providing a stable, multi-year regulatory framework for ComEd to recover its investments in grid modernization and energy efficiency, marking a turning point in the company’s relationship with Illinois regulators.
Exelon completes the strategic, tax-free spin-off of its competitive power generation business, Constellation Energy, transforming Exelon into a pure-play regulated electric and gas utility and eliminating all merchant power market exposure.
Calvin Butler Jr. assumes the role of President and Chief Executive Officer, initiating a comprehensive strategic focus on grid resilience, extreme weather hardening, and the execution of the company's massive, multi-billion-dollar capital expenditure program.
Exelon begins the massive operational and financial restructuring required to comply with the Climate and Equitable Jobs Act in Illinois, positioning ComEd as the central architect of the state's aggressive decarbonization and grid modernization mandates.
The company reports $20.8 billion in consolidated revenues and $1.7 billion in net income, while continuing its massive capital deployment into grid modernization, exceeding a consolidated regulated rate base of $35 billion.
The company acquired Pepco Holdings for $6.8 billion to instantly expand its regulated footprint into Washington D.C., Maryland, and Delaware, solidifying its position as the largest regulated utility in the United States by customer count and diversifying its geographic revenue base.
PECO Energy Company and Commonwealth Edison executed a landmark, $34 billion merger of equals to form Exelon Corporation, driven by the realization that the impending deregulation of the power markets required massive scale, operational efficiency, and financial firepower to survive.
Exelon Corporation was formed October 20, 2000 through merger of PECO Energy Company (Philadelphia Electric Company supporting Pennsylvania electric and gas operations) and Unicom Corporation (parent of Commonwealth Edison supporting Chicago and northern Illinois electric operations) creating largest US electric utility company at that time. Strategic rationale combined complementary geographic operations supporting various commercial benefits across Mid-Atlantic and Midwest US markets, scale economics supporting various operational efficiencies, substantial nuclear generation fleet (combined Exelon Generation operated largest US nuclear generation fleet representing approximately 20% of US nuclear electricity supporting various clean energy positioning), and various other strategic priorities. Subsequent strategic milestones include 2012 Constellation Energy merger ($7.9 billion supporting various Mid-Atlantic generation and competitive supply expansion), 2018 Pepco Holdings acquisition supporting Washington DC area utility expansion, 2022 transformational Constellation Energy spin-off (creating separately publicly traded Constellation Energy supporting Exelon strategic refocus on regulated transmission and distribution utility operations versus diversified power generation), and various other strategic moves. Revenue is $20.8 billion (2024) following various strategic transformations.
Exelon Corporation completed February 2022 spin-off of Constellation Energy Corporation creating separately publicly traded power generation company while Exelon retained regulated transmission and distribution utility operations supporting strategic refocus on regulated utility operations versus diversified power generation. Strategic rationale included continued regulated utility focus supporting various stable financial performance versus competitive generation operations with various commodity price exposure, simplified business portfolio supporting clearer strategic positioning, capital allocation flexibility supporting various continued operations, regulatory positioning supporting various rate-making activities, and various other strategic priorities. Post-spinoff Exelon focused on six regulated utility operations (ComEd Chicago/Illinois, PECO Pennsylvania, BGE Baltimore Maryland, Pepco Washington DC, Delmarva Power Delaware, Atlantic City Electric New Jersey supporting various Mid-Atlantic and Midwest US electric and gas operations), while Constellation Energy continued power generation including substantial nuclear fleet supporting various carbon-free baseload generation. Strategic implications include continued Exelon stable utility positioning supporting various stakeholder priorities, plus continued Constellation Energy positioning supporting various commodity price exposure through ongoing operational dynamics.
Exelon Corporation faces substantial data center industry electricity demand growth across ComEd Chicago operations plus various other service territories supporting potential transformational commercial benefits through continued capacity expansion requirements. Strategic context includes continued Northern Virginia data center industry dominance supporting various US data center growth, continued data center industry expansion across various Midwest markets including Chicago supporting ComEd capacity expansion opportunities, various AI infrastructure deployments supporting continued substantial electricity demand growth, plus various other operational considerations. Strategic implications include continued transmission and distribution infrastructure investment supporting capacity expansion requirements, regulatory navigation supporting various rate adjustments and capital recovery, environmental considerations affecting various generation supply (though Exelon as transmission-distribution utility doesn't directly operate generation following 2022 Constellation Energy spin-off), continued operational efficiency supporting various commercial benefits, and various other strategic considerations. Recent strategic activity includes continued infrastructure investment planning supporting data center demand growth, plus various other strategic moves supporting consolidated business performance through ongoing utility industry data center industry transformation.
Exelon Corporation completed Pepco Holdings Inc. acquisition in March 2016 (announced April 2014 followed by various regulatory approval processes) for $6.8 billion gaining substantial Mid-Atlantic utility operations including Pepco (Washington DC and Maryland), Delmarva Power (Delaware and Maryland), Atlantic City Electric (New Jersey) supporting strategic expansion in Mid-Atlantic regulated utility operations. Strategic rationale combined geographic expansion supporting various commercial benefits, scale economics across consolidated utility operations, regulated utility expansion supporting various stable financial performance, complementary operations with existing Exelon utilities (BGE Maryland operations supporting various regional integration), and various other strategic priorities. Post-acquisition integration was successful supporting continued utility operations across consolidated Mid-Atlantic operations with continued operational performance. Strategic value continues supporting current Exelon operations through six-utility footprint across Mid-Atlantic and Midwest US markets supporting various competitive positioning. The 2018 Pepco acquisition exemplifies major utility industry M&A supporting strategic expansion supporting consolidated business performance through ongoing operational dynamics affecting utility industry.