Mirant Corporation (NYSE: MIR) and RRI Energy, Inc. (NYSE: RRI) announced today that they have entered into a definitive agreement to create GenOn Energy, which will be one of the largest independent power producers in the United States, with approximately 24,700 megawatts (MW) of electric generating capacity and a pro forma market capitalization of $3.1 billion. The transaction is structured as an all-stock, tax-free merger.

Under the terms of the merger agreement, which has been approved unanimously by the Boards of Directors of both companies, Mirant stockholders will receive a fixed ratio of 2.835 shares of RRI Energy common stock for each share of Mirant common stock they own. The ratio reflects an at-market transaction based on the volume-weighted average price for the preceding 10 trading days. Upon closing, which is expected before the end of 2010, Mirant stockholders will own approximately 54% of the equity of the combined company and RRI Energy stockholders will own approximately 46%.

Edward R. Muller, chairman and chief executive officer of Mirant, will be chairman and chief executive officer of the combined company until 2013, when he plans to retire. Mark M. Jacobs, president and chief executive officer of RRI Energy, will be president and chief operating officer of GenOn and will serve on its board. Jacobs is to succeed Muller as CEO in 2013. J. William Holden III, currently chief financial officer of Mirant, will be chief financial officer of GenOn. The GenOn Board of Directors will be comprised of 10 directors, with five members of the current Mirant Board and the five members of the current RRI Energy Board. GenOn’s corporate headquarters will be located in Houston.

The merger brings together two organizations with complementary electric generating assets and proven operational excellence, enabling GenOn to derive substantial near- and long-term benefits from significant cost savings, greater scale, geographic diversity, and increased financial strength and flexibility. GenOn will have a strategically balanced presence across key regions, including the Mid-Atlantic, California, the Northeast, the Southeast and the Midwest.