1999: Constellation Energy Group Inc. becomes the holding company for BGE and related companies. Maryland passes an energy deregulation law.
2000: Constellation announces plan to split into two companies, BGE and a company to generate and sell power nationally.
2001: Constellation junks its plan to split. At the same time, it announces that Mayo A. Shattuck III, former chairman of Deutsche Banc Alex. Brown Inc., will become its chief executive officer. Christian H. Poindexter, who had led the company, retires.
2002: The company reduces its work force by 10 percent, reorganizes its management and closes its BGE Home retail stores.
Nov. 2005: Constellation and investment partners outline a $4 billion bid to buy the owner of Europe's largest coal-fired power plant, Drax Group Ltd. Drax shareholders reject the deal.
Dec. 2005: Constellation announces merger with FPL Group Inc.
Oct. 2006: Constellation and FPL scrap merger plans amid Maryland political fight over deregulation and higher electricity rates.
Sept. 2008: To avert a bankruptcy amid the financial crisis, Constellation agrees to a shotgun deal to sell itself to Warren Buffett's MidAmerican Energy Holdings for $4.7 billion.
Dec. 2008: Constellation terminates takeover agreement with MidAmerican to remain an independent company in Baltimore. Instead, the company gets a $4.5 billion investment from French utility EDF, its then-largest shareholder. In exchange, EDF gets nearly half of Constellation's nuclear power business.
April 2011: In a stock deal worth $7.9 billion, Constellation agrees to sell itself to Chicago-based Exelon Corp., becoming the largest energy provider in the U.S.