NRG Makes Unsolicited Offer for Calpine

Power generator Calpine Corp. confirmed that it received an unsolicited merger offer from NRG Energy Inc., which proposed a stock-for-stock transaction that would value the combined firm at $22 billion and create the largest independent power company in the U.S.

The NRG offer represented a 16% premium to Calpine's closing price when the offer was made on May 14 and a 6.7% premium to Wednesday's price. Under the proposal, NRG would give 0.534 share for each share of Calpine.

In 4 p.m. New York Stock Exchange composite trading Wednesday, Calpine was up eight cents to $21.28 and NRG was up ...