Debt-laden power producers such as Dynegy have seen their profit margins shrink, as cheap natural gas from shale fields drives electricity prices lower. Many power companies have merged this year as a result.
Dynegy shareholders will receive 0.652 shares of Vistra Energy for each share of Dynegy they own.
That translates to a price of $13.24 per share, representing a 43.8 percent premium to Dynegy's stock price on Tuesday, before The Wall Street Journal reported about merger talks between the two companies.
The deal is valued at $1.74 billion, based on the 131.37 million Dynegy shares outstanding, according to Thomson Reuters data.
The combined company will have a market value of more than $10 billion and will generate $350 million in earnings before income taxes and amortization on an annualized basis, Vistra and Dynegy said.
Houston-based Dynegy operates 27,000 megawatts of power generating facilities throughout the Northeast, Mid-Atlantic, Midwest, and Texas.
Vistra shareholders will own about 79 percent and Dynegy shareholders will own 21 percent stock of the combined company.
Dynegy shares rose 13 percent to $12.65 in premarket trading on Monday.