Short answers, pulled from the story.
Exelon Corporation is an American public utility headquartered in Chicago and incorporated in Pennsylvania. It is the largest regulated electric utility in the United States, serving approximately 10 million customers through six subsidiary utilities across the Mid-Atlantic and Midwest.
Exelon was created in October 2000 through the merger of PECO Energy Company, founded in 1902, and Unicom Corporation, the parent of Commonwealth Edison, founded in 1907. The merger was overseen by Unicom CEO John Rowe, who went on to lead Exelon until 2012.
Exelon owns six regulated utilities: Commonwealth Edison in Illinois, PECO Energy Company in Pennsylvania, Baltimore Gas and Electric in Maryland, Pepco in Washington D.C. and Maryland, Atlantic City Electric in New Jersey, and Delmarva Power in Delaware and the Eastern Shore of Maryland.
Exelon announced the purchase of Pepco Holdings on the 30th of April 2014, for $6.8 billion in an all-cash transaction. The deal faced opposition from community groups and D.C. Mayor Muriel Bowser, and was initially rejected by the District of Columbia Public Service Commission in August 2015. After Exelon made concessions, the commission approved the merger on the 23rd of March 2016.
Exelon's Braidwood Nuclear Generating Station, located 60 miles southwest of Chicago, spilled millions of gallons of water containing tritium multiple times over a decade. Exelon and Illinois state officials waited four years before disclosing the spills publicly in 2006. Exelon officials apologized and said tritium levels in surrounding wells were below regulatory limits.
Constellation Energy was Exelon's energy generation business, which was spun off as a separate company on the 2nd of February 2022. At the time of the spin-off, Constellation was the largest operator of nuclear power plants in the United States and the largest non-governmental nuclear operator in the world, with 23 reactors across 14 plants and approximately 35,500 megawatts of owned capacity.