Debt-laden power producer Calpine Corp said it agreed to be acquired by a consortium of investors led by Energy Capital Partners for $5.6 billion.
Calpine's shares were up 10.5 percent at $14.93 in premarket trading on Friday.
The $15.25 cash per share offer, represents a 13 percent premium to Calpine's closing price on Thursday.
The consortium includes billionaire industrialist Leonard Blavatnik's Access Industries and Canada Pension Plan Investment Board.
The Houston, Texas-based company relies mostly on natural gas to generate power and owns about 80 power plants in the United States and Canada.
Calpine said in July it was discussing a sale of the company after reporting a quarterly loss. The company's debt, as a net of current portion, was about $11.31 billion, as of June 30.
Lazard was Calpine's financial adviser and White & Case LLP was its legal adviser. Barclays Capital Inc was Energy Capital's financial adviser and Latham & Watkins LLP its legal adviser.
Reporting by John Benny