424(B)(3)
 

Filed Pursuant to Rule 424(b)(3)
Registration No. 333-123677
Prospectus Supplement No. 5 dated June 15, 2006
(To Prospectus dated June 2, 2005)
NRG LOGO
NRG Energy, Inc.
420,000 Shares of 4% Convertible Perpetual Preferred Stock
10,500,000 Shares of Common Stock issuable upon conversion of the Preferred Stock
      This Prospectus Supplement supplements the prospectus dated June 2, 2005 (the “Prospectus”) of NRG Energy, Inc., relating to the sale by certain of our stockholders (including their pledgees, donees, assignees, transferees, successors and others who later hold any of the selling stockholders’ interests) of up to 420,000 shares of preferred stock, or 10,500,000 shares of our common stock issuable upon conversion of the preferred stock. You should read this Prospectus Supplement in conjunction with the Prospectus, and this Prospectus Supplement is qualified by reference to the Prospectus, except to the extent that the information in this Prospectus Supplement supersedes the information contained in the Prospectus.
      Investing in our preferred stock or common stock involves risks that are described in the “Risk Factors” section beginning on page 6 of the Prospectus.
      Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this Prospectus Supplement is truthful or complete. Any representation to the contrary is a criminal offense.
The date of this Prospectus Supplement is June 15, 2006


 

The table of selling stockholders contained in the Prospectus is hereby superseded by the following table.
                                                 
                Securities Offered by the            
    Ownership Before Offering   Prospectus (1)     Ownership After Offering (2)
Name   Preferred     Common (3)   Preferred     Commons (3)     Preferred     Common     % of Common (4)
1976 Distribution Trust FBO A.R. Lauder/Zinterhofer
    6     150     6       150       0       0     *
2000 Revocable Trust FBO A.R. Lauder/Zinterhofer
    5     125     5       125       0       0     *
Advent Claymore Enhance Growth & Income Fund
    2,435     60,875     2,435       60,875       0       0     *
Advent Convertible Master (Cayman), L.P.
    6,723     168,075     6,723       168,075       0       0     *
Alcon Laboratories
    641     16,025     641       16,025       0       0     *
AM International EMAC 63 Ltd.
    790     19,750     790       19,750       0       0     *
AM Master Fund I, LP
    6,916     172,900     6,916       172,900       0       0     *
Anthony Munk
    607     15,175     607       15,175       0       0     *
Arlington County Employees Retirement Systems
    1,032     25,800     1,032       25,800       0       0     *
Asante Health Systems
    205     5,125     205       5,125       0       0     *
BBT Fund, L.P.
    8,850     221,250     8,850       221,250       0       0     *
Boston Income Portfolio c/o Eaton Vance Management High Yield Group
    1,255     31,375     1,255       31,375       0       0     *
Citigroup Global Markets, Inc.(5)
    5,000     125,000     5,000       125,000       0       0     *
City of New York Fire Dept Pension Fund High Yield(6)
    225     5,625     125       3,125       100       0     *
City of New York Police Pension Fund High Yield
    275     6,875     275       6,875       0       0     *
City of New York Teachers Retirement System High Yield(6)
    700     17,500     375       9,375       325       0     *
City University of New York
    215     5,375     215       5,375       0       0     *
CNHCA Master Account, LP
    5,500     137,500     5,500       137,500       0       0     *
Coastal Convertibles Ltd.
    1,500     37,500     1,500       37,500       0       0     *
Concentrated Alpha Partners LP
    6,750     168,750     6,750       168,750       0       0     *
DBAG London
    11,000     275,000     11,000       275,000       0       0     *
Delaware Dividend Income Fund
    1,500     37,500     1,500       37,500       0       0     *
Delaware Public Employees Retirement Systems
    1,857     46,425     1,857       46,425       0       0     *
Deutsche Bank Securities Inc.
    1,500     37,500     1,500       37,500       0       0     *

2


 

                                                   
                Securities Offered by the        
    Ownership Before Offering   Prospectus (1)     Ownership After Offering (2)  
Name   Preferred     Common (3)   Preferred     Commons (3)     Preferred     Common   % of Common (4)  
Diversified High Yield Bond Fund c/o Eaton Vance Management High Yield Group
    245     6,125     245       6,125       0       0     *  
Drawbridge Convertible I Ltd.
    489     12,225     489       12,225       0       0     *  
Drawbridge Convertible II Ltd.
    156     3,900     156       3,900       0       0     *  
Drawbridge Global Macro Masterfund Ltd.
    3,310     82,750     3,310       82,750       0       0     *  
ELCA Unscreened — High Yield(6)
    525     13,125     275       6,875       250       0     *  
FIST Convertible Secs FD
    10,000     250,000     10,000       250,000       0       0     *  
Fidelity Financial Trust: Fidelity
Strategic Dividend & Income Fund(7)(8)
  4,900     122,500     3,900       97,500       0       0     *  
Fore Convertible Master Fund, Ltd.
    25,220     630,500     25,220       630,500       0       0     *  
Fore Erisa Fund, Ltd.
    2,790     69,750     2,790       69,750       0       0     *  
Frontpoint Convertible Arbitrage Fund LP
    5,000     125,000     5,000       125,000       0       0     *  
GLG Market Neutral Fund
    22,000     550,000     22,000       550,000       0       0     *  
Grace Convertible Arbitrage Fund, Ltd.
    7,000     175,000     7,000       175,000       0       0     *  
Grady Hospital
    201     5,025     201       5,025       0       0     *  
Guggenheim Portfolio Company VIII (Cayman) Ltd.
    2,511     62,775     2,511       62,775       0       0     *  
Guggenheim Portfolio Company XXXI, LLC
    5,000     125,000     5,000       125,000       0       0     *  
Hallmark Master Trust High Yield Fund c/o Eaton Vance Management High Yield Group
    70     1,750     70       1,750       0       0     *  
HFR CA Opportunity Mgt. Trst.
    340     8,500     340       8,500       0       0     *  
HFR CA Select Fund
    750     18,750     750       18,750       0       0     *  
HFR RVA Combined Master Trust
    2,000     50,000     2,000       50,000       0       0     *  
High Income Portfolio c/o Eaton Vance Management High Yield Group
    865     21,625     865       21,625       0       0     *  
IAM National Pension Fund(6)
    350     8,750     175       4,375       175       0     *  
Independence Blue Cross
    623     15,575     623       15,575       0       0     *  
Industriens Pensionsforsikring(6)
    325     8,125     175       4,375       150       0     *  

3


 

                                                     
                Securities Offered by the              
    Ownership Before Offering   Prospectus (1)     Ownership After Offering (2)    
Name   Preferred     Common (3)   Preferred     Commons (3)     Preferred     Common   % of Common (4)    
ING Convertible Fund
    1,920     48,000     1,920       48,000       0       0   *    
ING CP Convertible Portfolio
    80     2,000     80       2000       0       0   *    
ING MFS Utilities Portfolio
    40     79,520     40       1,000       0       78,520   *    
ING Investors Trust — ING T. RowePrice Capital Appreciation Portfolio(6)
    8,600     215,000     8,600       215,000       0       0   *    
Institutional Benchmarks Master Fund, Ltd.
    1,500     37,500     1,500       37,500       0       0   *    
Intl Union of Operating Engineers (ENG) c/o Eaton Vance Management High Yield Group
    15     375     15       375       0       0   *    
JHVST MidCap Value B
    200     52,200     200       5,000       0       47,200   *    
JMG Capital Partners, Inc
    34,500     862,500     34,500       862,500       0       0   *    
JMG Triton Offshore Ltd.
    2,850     71,250     2,850       71,250       0       0   *    
John Hancock Funds II — Spectrum Income Fund(6)
    250     6,250     100       2,500       150       0   *    
John Hancock Trust — Spectrum Income Trust(6)
    225     5,625     100       2,500       125       0   *    
John Hancock Trust Utilities Trust
    100     133,640     100       2,500       0       131,140   *    
John Hancock Trust — Mid Value Trust
    200     18,800     200       5,000       0       13,800   *    
JP Morgan Securities, Inc.
    2,500     62,500     2,500       62,500       0       0   *    
Kamunting Street Master Fund, Ltd.
    15,000     375,000     15,000       375,000       0       0   *    
KBC Financial Products USA, Inc.
    8,955     223,875     8,955       223,875       0       0   *    
KDC Convertible Arbitrage Fund LP
    3,000     75,000     3,000       75,000       0       0   *    
Laborers District Council & Contractors Pension FD of Ohio(6)
    200     10,300     200       5,000       0       5,300   *    
LIJ Invest — Global High Yield
    275     6,875     275       6,875       0       0   *    
Lyxor
    465     11,625     465       11,625       0       0   *    
Lyxor/AM Investment Fund Ltd.
    988     24,700     988       24,700       0       0   *    
Lyxor/Silverado Fund LTD
    1,550     38,750     1,550       38,750       0       0   *    
Man Mac I, Ltd.
    9,390     234,750     9,390       234,750       0       0   *    
McMahan Securities Co. LP
    45     1,125     45       1,125       0       0   *    

4


 

                                                   
                Securities Offered by the        
    Ownership Before Offering   Prospectus (1)     Ownership After Offering (2)  
Name   Preferred     Common (3)   Preferred     Commons (3)     Preferred     Common     % of Common (4)
MFS Utilities Fund, a Series of MFS Series Trust VI
    1,355     1,614,875     1,355       33,875       0       1,581,000       1.15%
MFS Variable Insurance Trust -
MFS Utilities Series
    820     874,400     820       20,500       0       853,900       *
MFS/Sun Life Series Trust:
                                                 
Utilities Series
    324     363,800     324       8,100       0       355,700       *
MSS Convertible Arbitrage 1
    20     500     20       500       0       0       *
National Bank of Canada
    1,186     29,650     1,186       29,650       0       0       *
New Orleans Firefighters Pension/Relief Fund
    126     3,150     126       3,150       0       0       *
New York City Employees Retirement Systems Enhanced Fund(6)
    875     21,875     475       11,875       400       0       *
Newport Alternative Income Fund
    2,972     74,300     2,972       74,300       0       0       *
NMS Services (Cayman) Inc.
    752     18,800     752       18,800       0       0       *
Northern Income Equity Fund
    2,460     61,500     2,460       61,500       0       0       *
Occidental Petroleum Corporation
    114     2,850     114       2,850       0       0       *
Pebble Limited Partnership
    2,083     52,075     2,083       52,075       0       0       *
Penn Series Flexibly Managed Fund
    5,600     140,000     5,600       140,000       0       0       *
Penn Series High Yield Bond Fund
    200     5,000     200       5,000       0       0       *
PensionsInvest — Global High Yield(6)
  250     6,250     250       6,250       0       0       *
PFA Invest — Global High Yield(6)
    800     20,000     450       11,250       350       0       *
PIMCO Convertible Fund
    500     12,500     500       12,500       0       0       *
Policeman and Fireman Retirement System of the City of Detroit
    500     12,500     500       12,500       0       0       *
Pro-Mutual
    1,357     33,925     1,357       33,925       0       0       *
RWDSU Local 338 High Yield Fund c/o Eaton Vance Management High Yield Fund
    20     500     20       500       0       0       *
S.A.C. Arbitrage Fund, LLC
    8,000     200,000     8,000       200,000       0       0       *
Sage Capital Management LLC
    3,000     75,000     3,000       75,000       0       0       *
Salomon Brothers Asset Management, Inc.(9)
    6,600     165,000     6,600       165,000       0       0       *
SEPTA High Yield Fund c/o Eaton Vance Management High Yield Group
    20     500     20       500       0       0       *

5


 

                                                     
                Securities Offered by the        
    Ownership Before Offering   Prospectus (1)     Ownership After Offering (2)  
Name   Preferred     Common (3)   Preferred     Commons (3)     Preferred     Common     % of Common (4)
Severn River Master Fund c/o Morgan Stanley
    1,000     25,000     1,000       25,000       0       0       *
Silver Point Capital Fund LP
    1,365     1,042,333     1,365       34,125       0       1,008,208       *
Silver Point Capital Offshore Fund, Ltd.
    2,135     1,654,740     2,135       53,375       0       1,601,365       1.17%
Silverado Arbitrage Trading, Ltd.
    500     22,500     500       12,500       0       10,000       *
SOCS Ltd.
    10,000     260,000     8,000       250,000       2,000       10,000       *
Sphinx Fund
    140     3,500     140       3,500       0       0       *
SRI Fund, L.P.
    1,500     37,500     1,500       37,500       0       0       *
Stanfield Offshore Leveraged Assets, Ltd.
    10,500     693,213     10,500       262,500       0       430,713       *
T. RowePrice Capital Appreciation Fund(6)
    23,400     585,000     23,400       585,000       0       0       *
T. RowePrice High Yield Fund(6)
    8,550     213,750     4,350       108,750       4,200       0       *
T. RowePrice Capital Appreciation Trust(6)
    300     7,500     300       7,500       0       0       *
T. RowePrice Mid-Cap Value Fund(6)
    12,000     640,800     12,000       300,000       0       340,800       *
The New America High Income Fund
    375     9,375     375       9,375       0       0       *
TQA Master Fund, LTD.
    870     21,750     870       21,750       0       0       *
TQA Masters Plus Fund, LTD.
    1,510     37,750     1,510       37,750       0       0       *
TRP Institutional High Yield Fund
    375     9,375     375       9,375       0       0       *
TRP Invest — Global High Yield(6)
    1,950     48,750     350       8,750       1,600       0       *
TRP SICAV Global High Yield Bond Fund
    1,125     28,125     1,125       28,125       0       0       *
Trustmark Insurance
    393     9,825     393       9,825       0       0       *
UBS AG London FBO HFS
    5,000     125,000     5,000       125,000       0       0       *
UBS AG London FBO PFEL
    18,500     462,500     18,500       462,500       0       0       *
UBS AG London FBO WCBP
    20,000     500,000     20,000       500,000       0       0       *
UBS O’Connor LLC FBO O’Connor Global Convertible Arbitrage Master Ltd.
    4,561     114,025     4,561       114,025       0       0       *
Volkswagen High Yield Bond Fund c/o Eaton Vance Management High Yield Group
    10     250     10       250       0       0       *
Whitebox Convertible Arbitrage Partners LP
    26,000     650,000     26,000       650,000       0       0       *
Whitebox Diversified Convertible Arbitrage Partners LP
    5,000     125,000     5,000       125,000       0       0       *

6


 

                                                     
                Securities Offered by the        
    Ownership Before Offering   Prospectus (1)     Ownership After Offering (2)  
Name   Preferred     Common (3)   Preferred     Commons (3)     Preferred     Common     % of Common (4)
Xavex – Convertible Arbitrage 7 Fund
    150     3,750     150       3,750       0       0       *
Zazove Convertible Arbitrage Fund, LP
    4,000     100,000     4,000       100,000       0       0       *
Zazove Hedged Convertible Fund, LP
    2,000     50,000     2,000       50,000       0       0       *
Zurich Institutional Benchmarks Master Fund LTD c/o TQA Investors, LLC
    180     4,500     180       4,500       0       0       *
Zurich Institutional Benchmarks Master Fund Ltd. c/o Forest Investment LLC
    2,061     51,525     2,061       51,525       0       0       *

7


 

 
* Less than 1%.
(1)  Amounts indicated may be in excess of the total amount registered due to sales or transfers exempt from the registration requirements of the Securities Act of 1933, as amended, since the date upon which the selling stockholders provided to us the information regarding their preferred stock.
 
(2)  The information regarding the beneficial ownership after resale of shares is based on the assumption that each selling stockholder will sell all of the shares of preferred stock and common stock owned by the selling stockholder and covered by the Prospectus.
 
(3)  Unless otherwise indicated, includes all shares of common stock issuable upon conversion of the preferred stock and assumes a conversion price of $40.00 per share, which is equal to an approximate conversion rate of 25 shares per share of preferred stock. However, this conversion price will be subject to adjustment as described under “Description of the Preferred Stock — Conversion Rights” in the Prospectus. As a result, the number of shares of common stock beneficially owned prior to this offering and the number of shares of common stock offered hereby may increase or decrease in the future.
 
(4)  Based on 136,979,082 shares of common stock outstanding as of June 14, 2006.
 
(5)  Citigroup Global Markets Inc. was a co-placement agent on the issuance of the preferred stock.
 
(6)  T. Rowe Price Associates, Inc. serves as investment adviser with power to direct investments and/or sole power to vote the shares owned by certain funds and accounts subject this footnote, as well as shares owned by certain other individual and institutional investors. For purposes of reporting requirements of the Securities and Exchange Act of 1934, T. Rowe Price Associates, Inc. may be deemed to be the beneficial owner of all of the shares listed above that are subject to this footnote; however, T. Rowe Price Associates, Inc. expressly disclaims that it is in fact the beneficial owner of such securities. T. Rowe Price Associates, Inc. is the wholly owned subsidiary of T. Rowe Price Group, Inc., which is a publicly traded financial services holding company.
 
(7)  The entity is a registered investment fund advised by Fidelity Management & Research Company (“FMR Co.”), a registered investment adviser under the Investment Advisers Act of 1940, as amended. FMR Co., 82 Devonshire Street, Boston, Massachusetts 02190, a wholly-owned subsidiary of FMR Corp. and an investment adviser registered under Section 203 of the Investment Advisers Act of 1940, is the beneficial owner of 2,402,699 shares of our outstanding common stock as a result of acting as investment adviser to various investment companies registered under Section 8 of the Investment Company Act of 1940.
 
(8)  Based on information provided by the selling stockholder and, in addition to the preferred stock and common stock covered by this prospectus, includes beneficial ownership of our 5.75% Mandatory Convertible Preferred Stock, as well as the common stock to be issued upon conversion of such preferred stock.
 
(9)  Salomon Brothers Asset Management, Inc. acts as discretionary investment advisor with respect to certain accounts that hold the preferred stock. Accordingly, Salomon Brothers Asset Management, Inc. may be deemed to be the beneficial owner of such preferred stock. Salomon Brothers Asset Management, Inc. is the beneficial owner and, therefore, the Selling Stockholder of the following accounts: General Motors Investment Corp. (5,000 shares), General Motors Broad Mandate (600 shares) and Smith Barney Convertible Fund (1,000 shares).

8