We urge you to vote today using theBLUE proxy card-by telephone by Internet or by signing dating and returningthe BLUE proxy card

We urge you to vote today using theBLUE proxy card-by telephone, by Internet or by signing, dating and returningthe BLUE proxy card in the postage-paid envelope provided. SETTING THE RECORD STRAIGHTSince we publicly disclosed our proposal, you have been subjected to what webelieve is an unfortunate amount of misinformation and distortion coming fromNRG. Of late, in particular, NRG`s management has sought to disparage the truevalue of Exelon`s offer. The fact is that Exelon`s offer is worth more today than it was in October 2008.Investors are already well aware of the extent to which the value of Exelon`soffer has supported the trading price of NRG`s stock for more than eight months.Beyond that, it`s important to focus on a few of the key value drivers thatExelon will bring to the combined company in the future. EXELON`S VALUE PROPOSITION: STRONGER TODAY, STRONGER TOMORROW1. Strength and Scale.Exelon`s position in the competitive power sector - withthe largest nuclear fleet in the country and the third largest in the world -cannot be replicated. Exelon has the largest market cap in the industry andmaintains an investment grade credit rating.

This represents a sustainablecompetitive advantage, with scale, scope and financial flexibility becomingincreasingly important for competitive generators. Given the highly volatilemarket environment and unprecedented political/regulatory challenges, smaller,sub-investment grade companies like NRG with concentrated risks will facegrowing challenges over the long-term. The combined Exelon-NRG will have scaleunparalleled in the industry, with considerable regional, fuel and regulatorydiversity, and with the financial strength and flexibility required to endurecommodity fluctuations, political risks and capital market constraints 2 Carbon Advantage. Climate change legislation is now more likely than ever,and will significantly increase Exelon`s long-term earnings and valueproposition while reducing the long-term value of NRG`s coal-powered generationfleet. While the specific provisions of legislation that may ultimately beapproved are subject to further debate, Exelon`s large nuclear fleet positionsitfor significant upside from virtually any form of carbon legislation.

At thesame time, NRG will face long-term downside risk as a stand-alone entitydominated by coal plants.3 Increased Nuclear Capacity. Exelon intends to bring on-line between 1,300 and1,500 MW of nuclear uprates between now and 2017 - representing the equivalentof a new nuclear unit at roughly half the cost to build, and with no incrementalannual operating expense other than the cost of fuel. Nuclear uprates provide asubstantially higher return at lower financial risk than new build, and do notpresent the substantial risk of new-build cost overruns and regulatory delays,including those that NRG faces with its proposed new nuclear build at SouthTexas. The uprate projects are expected to be financed through Exelon`s balancesheet capacity. By comparison, NRG`s likely share of the output of its proposednuclear project will be less than the amount of these uprates, while thefinancial risks of that project are substantially greater than Exelon`s uprates.While Exelon has successfully brought 1,100 MW of uprates on line over the pastten years and has plans to do even more, NRG is taking substantial risk tofinance and build a $10 billion nuclear plant as a sub-investment grade company- something NRG has never done before and will not be able to do withoutfinancial assistance well in excess of the limited DOE loan guarantee resourcesthat may be available to NRG for its project 4. Cost Discipline.Exelon has demonstrated a commitment to shareholder valuethrough successful cost-cutting programs, including a recently announcedefficiency program.

O&M cost savings of $350 million are in the plan for 2010,half of which will be sustainable, representing a 3.5% decrease in O&M from 2009to 2010. Exelon has a history of successfully creating shareholder value throughdisciplined spending, including $250 million of O&M cost savings following theUnicom-PECO merger in 2000 and another $350 million in O&M cost savings drivenby the Exelon Way in 2003-2004. 5.Market Diversification.Recent procurement events by Allegheny Power and PECOEnergy in Pennsylvania, in which Exelon Generation won commitments for over 7million megawatt hours of generation supply beginning in 2011, provide evidenceof strong pricing for Exelon`s MidAtlantic fleet.The retail prices clearlyunderscore the long-term value inherent in Exelon`s well-positioned assets andthe importance of strong regional market diversification.We believe a combination of Exelon and NRG represents compelling and substantialvalue for all NRG stockholders. We also believe thatthe quickest and clearestpath for NRG stockholders to realize the benefits of a transaction with Exelon -or any other strategic transaction - is to elect directors to the NRG board whoare open to considering the merits of a combined Exelon-NRG and will compelmanagement to at least enter into serious discussions on a transaction thatdemonstrates such clear value to you.VOTE THE BLUE PROXY CARD TODAYAt the end of the day, you, as stockholders, are the owners of NRG and you willultimately determine the future of your investment, but we do not think you willhave that opportunity without a change in the NRG board.

We are confident thatyou want a board of directors that will give Exelon`s offer full and fairconsideration. We are equally confident that the nine independent nominees onthe BLUE proxy card, upon election to the NRG board, will give fullconsideration to all strategic alternatives available to NRG and will notneglect, as we believe the current NRG board has, the opportunity to enter intoa transaction that promises to create superior value for you Your vote is extremely important. To elect directors who are committed tolooking out for your best interests, including exploring a potential combinationof Exelon and NRG, please vote the BLUE proxy card TODAY by telephone, byInternet, or by signing, dating and returning the enclosed BLUE proxy card inthe postage-paid envelope provided Thank you for your consideration Sincerely, John W. Rowe Chairman and Chief Executive Officer Exelon Corporation* * * * Exelon announced on June 17, 2009, that it had filed its definitive proxymaterials with the Securities and Exchange Commission to solicit proxies fromNRG shareholders at the NRG annual meeting of shareholders scheduled for July21, 2009.