PRINCETON - NRG Energy Inc. said today that it will hold its annual meeting July 21, when Exelon Corp. is expected to push for a revised board of directors as part of a takeover bid.

Chicago-based Exelon, which owns Peco Energy Co. of Philadelphia, is attempting to take over NRG Energy in a $5 billion deal that would create the nation's largest power generator. The combined company would be big enough to power nearly 45 million homes.

NRG Energy has resisted Exelon's overtures, saying the offer undervalues the company.

Both Exelon and NRG Energy have nominated a slate of directors for shareholders to vote on at the meeting. The outcome of that vote could ultimately determine whether the sale goes through.

NRG Energy said today that its current board recommends shareholders vote against Exelon's slate of directors and an Exelon proposal to increase the board's size.

Shares of NRG Energy rose 24 cents to $22.61 in afternoon trading. Exelon gained 46 cents to $48.73.