Constellation is in talks to buy Calpine in a transaction that would value the power company at close to $30 billion, including debt, the people said. The deal is exp

Constellation Energy Corp. is nearing an acquisition of Calpine Corp., people familiar with the matter said, in what would be one of the biggest ever deals in the power generation sector.

Shares of Constellation Energy Corp. CEG slid 4.61% to $243.84 Wednesday, on what proved to be an all-around great trading session for the stock market, with the S&P 500 Index SPX rising 0.16% to 5,918.

Constellation Energy shares fell roughly 5% after reports it is in advanced talks to acquire closely held Calpine in a cash-and-stock deal. Shares in Constellation, the largest U.S. owner of nuclear-power plants,

S&P 500 nuclear stock Constellation Energy fell in afternoon trade on Wednesday after a report emerged that it's close to finalizing a deal for Calpine, a natural gas and geothermal power generator. Constellation Energy is in discussions with Calpine's private-equity owners about a deal that could value the company at about $30 billion including debt,