Dynergy Inc. says it plans to be acquired by the Blackstone Group for $542.7 million.

Including the assumption of debt, the companies value the deal at $4.7 billion.

Dynergy said Friday its shareholders would receive $4.50 per share in cash for the nearly 120.6 million shares outstanding, representing a 62 percent premium from the closing price on Thursday.

Shares jumped $1.77, nearly 64 percent, to $4.55 in pre-market trading.

Dynergy, based in Houston, separately agreed to sell four gas-fired power plants to NRG Energy for $1.36 billion in cash.