A week and a half has passed since Exelon Corp made its unsolicited bid for NRG Energy Inc. But NRG still kept mum on the offer in both its third-quarter earnings pres release and its conference call with investers on Thursday morning.

“Our board is continuing to review the proposal,” Nahla Azmy, NRG’s director of investor relations said on the conference call. ”With that said, please keep in mind the purpose of today’s call is to discuss our third quarter performance and thus we will will not be making any formal remarks nor commenting on any aspects of Exelon’s proposal until an official board response has been issued.” 

So what does the lack of action mean?

“We think this might indicate that NRG is looking at a variety of alternatives beyond simply accepting the offer or remaining a stand-alone company,” Wachovia analyst Samuel Brothwell said in a research note.

Or perhaps NRG is waiting to see whether Exelon – which has suggested it would make a hostile bid if it is rebuffed by NRG – plans to back up its words with action. Your move, Exelon?