Constellation Energy Corporation is an American energy company headquartered in Baltimore, Maryland. The company provides electric power, natural gas, and energy management services. It has approximately two million customers across the continental United States. The company was known as Constellation Energy Group, a Fortune 500 company and one of the largest electricity producers in the United States, until a merger with Exelon in 2012. When FERC approved the acquisition, Constellation Energy's energy supply business was re-branded as Constellation, an Exelon company. As part of the 2012 merger, Baltimore Gas and Electric, the regulated utility operated by Constellation Energy, became a regulated utility operating under Exelon Utilities. The current iteration of the company was founded in 2022 after splitting off from Exelon. Before merging with Exelon, Constellation Energy Group operated more than 35 power plants in 11 states. Baltimore Gas and Electric created Constellation as a holding company in 1999.