NRG bids to buy Calpine

Hoping to double its electricity capacity, power wholesaler NRG Energy Inc. has offered to buy hobbled rival Calpine Corp. for about $11.3 billion in stock.

Calpine, a San Jose-based power producer, revealed details of the unsolicited bid Wednesday after a shareholder released a letter stating that an offer had been made last week.

NRG, based in Princeton, N.J., confirmed the offer, made May 14. The bid, initially valued at $22.98 a share, was worth $22.70 a share Wednesday, putting the cost for 500 million shares it needs at $11.3 billion.

The takeover attempt comes less than four months after Calpine emerged from a two-year stint operating under Chapter 11 bankruptcy protection. During that time, Calpine jettisoned more than 1,000 employees, or a third of its workforce, and reorganized more than $20 billion in debt.

More layoffs are likely if NRG’s offer is accepted. NRG said it believed that it could lower annual expenses by about $100 million by eliminating duplicative jobs and other overlapping operations.