Exelon Corporation and Constellation Energy have completed the $7.9 billion merger, announced last May. The combined company, which retains the Exelon name, becomes the largest nuclear power plant operator in the United States by an even bigger margin with a fleet of 22 nuclear power plants (19.0 GW).

Christopher M. Crane is president and CEO of the ‘new’ Exelon, and Mayo A. Shattuck III is executive chairman. The new company remains headquartered in Chicago, with significant operations in Maryland, Illinois and Pennsylvania. It will trade on the New York Stock Exchange under the symbol EXC.

“Today, the State of Maryland and City of Baltimore become an important new home for Exelon, joining Chicago and Philadelphia,” said Crane. “The combined strengths of Exelon and Constellation provide a solid platform for the future.”

Exelon claims that the merged company is now one of the nation’s largest competitive energy products and services suppliers by load (164 TWh per year) and customers (100,000 business and public sector and 1 million residential). The company also has 35 GW of ‘clean’ generating capacity, including the 19 GW of nuclear.

The two companies are combining operations immediately, and integration efforts are well underway, Exelon said.