REFILE-UPDATE 1-NRG made bid for Calpine-shareholder

(Refiles to fix company name of NRG Energy Inc)

(Adds details, closing stock prices)

NEW YORK, May 21 (Reuters) - A Calpine Corp (CPN.N: Quote, Profile, Research) shareholder on Wednesday said the power company has received a merger bid from competitor NRG Energy Inc. (NRG.N: Quote, Profile, Research)

According to hedge fund Harbinger Capital Partners, NRG proposed merging with Calpine at a premium to the company's May 14 share price.

Harbinger said it believes the offer represents a good starting point, and that Calpine's board should immediately negotiate with NRG over terms.

Neither company was immediately available for comment.

NRG shares closed up 36 cents to $42.51, while Calpine added 8 cents to $21.28, both on the New York Stock Exchange (Reporting by Michael Erman; editing by Jeffrey Benkoe)