UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934
                               (Amendment No. 1)*

                                NRG ENERGY, INC.
--------------------------------------------------------------------------------
                                (Name of Issuer)

                     Common Stock, $0.01 Par Value Per Share
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    629377508
                                    ---------
                                 (CUSIP Number)


                                December 31, 2006
                                -----------------
                      (Date of Event which Requires Filing
                               of this Statement)



Check the appropriate box to designate the rule pursuant to which this Schedule
is filed:

          [ ]     Rule 13d-1(b)
          [X]     Rule 13d-1(c)
          [ ]     Rule 13d-1(d)



*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).


                                  Page 1 of 11





-------------------                                           ------------------
CUSIP No. 629377508                   13G                     Page 2 of 11 Pages
-------------------                                           ------------------

---------- ---------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           S.A.C. Capital Advisors, LLC
---------- ---------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                      (a) [ ]
                                                                      (b) [X]
---------- ---------------------------------------------------------------------
        3  SEC USE ONLY

---------- ---------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware
--------------------- ----- ----------------------------------------------------
                         5  SOLE VOTING POWER

                            0
NUMBER OF             ----- ----------------------------------------------------
SHARES                   6  SHARED VOTING POWER
BENEFICIALLY
OWNED                       1,676,200 (see Item 4)
BY                    ----- ----------------------------------------------------
EACH                     7  SOLE DISPOSITIVE POWER
REPORTING
PERSON                      0
WITH                  ----- ----------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            1,676,200 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           1,676,200 (see Item 4)
---------- ---------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           [ ]

---------- ---------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           1.3% (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           00
---------- ---------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT


                                  Page 2 of 11





-------------------                                           ------------------
CUSIP No. 629377508                   13G                     Page 3 of 11 Pages
-------------------                                           ------------------

---------- ---------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           S.A.C. Capital Management, LLC
---------- ---------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                      (a) [ ]
                                                                      (b) [X]
---------- ---------------------------------------------------------------------
        3  SEC USE ONLY

---------- ---------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware
--------------------- ----- ----------------------------------------------------
                         5  SOLE VOTING POWER

                            0
NUMBER OF             ----- ----------------------------------------------------
SHARES                   6  SHARED VOTING POWER
BENEFICIALLY
OWNED                       1,676,200 (see Item 4)
BY                    ----- ----------------------------------------------------
EACH                     7  SOLE DISPOSITIVE POWER
REPORTING
PERSON                      0
WITH                  ----- ----------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            1,676,200 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           1,676,200 (see Item 4)
---------- ---------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           [ ]

---------- ---------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           1.3% (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           00
---------- ---------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT


                                  Page 3 of 11





-------------------                                           ------------------
CUSIP No. 629377508                   13G                     Page 4 of 11 Pages
-------------------                                           ------------------

---------- ---------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           S.A.C. Capital Associates, LLC
---------- ---------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                      (a) [ ]
                                                                      (b) [X]
---------- ---------------------------------------------------------------------
        3  SEC USE ONLY

---------- ---------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           Anguilla, British West Indies
--------------------- ----- ----------------------------------------------------
                         5  SOLE VOTING POWER

                            0
NUMBER OF             ----- ----------------------------------------------------
SHARES                   6  SHARED VOTING POWER
BENEFICIALLY
OWNED                       1,640,600 (see Item 4)
BY                    ----- ----------------------------------------------------
EACH                     7  SOLE DISPOSITIVE POWER
REPORTING
PERSON                      0
WITH                  ----- ----------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            1,640,600 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           1,640,600 (see Item 4)
---------- ---------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           [ ]

---------- ---------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           1.3% (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           00
---------- ---------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT


                                  Page 4 of 11





-------------------                                           ------------------
CUSIP No. 629377508                   13G                     Page 5 of 11 Pages
-------------------                                           ------------------

---------- ---------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           CR Intrinsic Investors, LLC
---------- ---------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                      (a) [ ]
                                                                      (b) [X]
---------- ---------------------------------------------------------------------
        3  SEC USE ONLY

---------- ---------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware
--------------------- ----- ----------------------------------------------------
                         5  SOLE VOTING POWER

                            0
NUMBER OF             ----- ----------------------------------------------------
SHARES                   6  SHARED VOTING POWER
BENEFICIALLY
OWNED                       2,072,200 (see Item 4)
BY                    ----- ----------------------------------------------------
EACH                     7  SOLE DISPOSITIVE POWER
REPORTING
PERSON                      0
WITH                  ----- ----------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            2,072,200 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           2,072,200 (see Item 4)
---------- ---------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           [ ]

---------- ---------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           1.6% (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           00
---------- ---------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT


                                  Page 5 of 11





-------------------                                           ------------------
CUSIP No. 629377508                   13G                     Page 6 of 11 Pages
-------------------                                           ------------------

---------- ---------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           Steven A. Cohen
---------- ---------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                      (a) [ ]
                                                                      (b) [X]
---------- ---------------------------------------------------------------------
        3  SEC USE ONLY

---------- ---------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           United States
--------------------- ----- ----------------------------------------------------
                         5  SOLE VOTING POWER

                            0
NUMBER OF             ----- ----------------------------------------------------
SHARES                   6  SHARED VOTING POWER
BENEFICIALLY
OWNED                       3,748,400 (see Item 4)
BY                    ----- ----------------------------------------------------
EACH                     7  SOLE DISPOSITIVE POWER
REPORTING
PERSON                      0
WITH                  ----- ----------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            3,748,400 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           3,748,400 (see Item 4)
---------- ---------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           [ ]

---------- ---------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           3.0% (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           IN
---------- ---------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT


                                  Page 6 of 11





Item 1(a)           Name of Issuer:
                    --------------

                    NRG Energy, Inc.

Item 1(b)           Address of Issuer's Principal Executive Offices:
                    -----------------------------------------------

                    211 Carnegie Center
                    Princeton, New Jersey  08540

Items 2(a)          Name of Person Filing:
                    ---------------------

                    This statement is filed by: (i) S.A.C. Capital Advisors,
                    LLC, ("SAC Capital Advisors") with respect to shares of
                    common stock, $.01 par value per share ("Shares"),
                    beneficially owned by S.A.C. Capital Associates, LLC ("SAC
                    Capital Associates") and S.A.C. MultiQuant Fund, LLC ("SAC
                    MultiQuant"); (ii) S.A.C. Capital Management, LLC, ("SAC
                    Capital Management") with respect to Shares beneficially
                    owned by SAC Capital Associates and SAC MultiQuant; (iii)
                    SAC Capital Associates with respect to Shares beneficially
                    owned by it; (iv) CR Intrinsic Investors, LLC ("CR Intrinsic
                    Investors") with respect to Shares beneficially owned by CR
                    Intrinsic Investments, LLC ("CR Intrinsic Investments"); and
                    (v) Steven A. Cohen with respect to Shares beneficially
                    owned by SAC Capital Advisors, SAC Capital Management, SAC
                    Capital Associates, SAC MultiQuant, CR Intrinsic Investors
                    and CR Intrinsic Investments.

                    SAC Capital Advisors, SAC Capital Management, SAC Capital
                    Associates, CR Intrinsic Investors and Steven A. Cohen have
                    entered into a Joint Filing Agreement, a copy of which is
                    filed with this Schedule 13G as Exhibit 99.1, pursuant to
                    which they have agreed to file this Schedule 13G jointly in
                    accordance with the provisions of Rule 13d-1(k) of the
                    Securities Exchange Act of 1934, as amended.


Item 2(b)           Address of Principal Business Office:
                    ------------------------------------

                    The address of the principal business office of (i) SAC
                    Capital Advisors, CR Intrinsic Investors and Mr. Cohen is 72
                    Cummings Point Road, Stamford, Connecticut 06902; (ii) SAC
                    Capital Management is 540 Madison Avenue, New York, New York
                    10022 and (iii) SAC Capital Associates is P.O. Box 58,
                    Victoria House, The Valley, Anguilla, British West Indies.

Item 2(c)           Citizenship:
                    -----------

                    SAC Capital Advisors, SAC Capital Management and CR
                    Intrinsic Investors are Delaware limited liability
                    companies. SAC Capital


                                  Page 7 of 11





                    Associates is an Anguillan limited liability company. Mr.
                    Cohen is a United States citizen.

Item 2(d)           Title of Class of Securities:
                    ----------------------------

                    Common Stock, par value $0.01 per share

Item 2(e)           CUSIP Number:
                    ------------

                    629377508

Item 3              Not Applicable

Item 4              Ownership:
                    ---------

                    The percentages used herein are calculated based upon the
                    Shares issued and outstanding as of November 2, 2006 as
                    reported on the Issuer's quarterly report on Form 10-Q filed
                    with the Securities and Exchange Commission by the Issuer
                    for the quarterly period ended September 30, 2006.

                    As of the close of business on December 31, 2006:

                    1. S.A.C. Capital Advisors, LLC
                    (a) Amount beneficially owned: 1,676,200
                    (b) Percent of class: 1.3%
                    (c)(i) Sole power to vote or direct the vote: -0-
                    (ii) Shared power to vote or direct the vote: 1,676,200
                    (iii) Sole power to dispose or direct the disposition: -0-
                    (iv) Shared power to dispose or direct the disposition:
                    1,676,200

                    2. S.A.C. Capital Management, LLC
                    (a) Amount beneficially owned: 1,676,200
                    (b) Percent of class: 1.3%
                    (c)(i) Sole power to vote or direct the vote: -0-
                    (ii) Shared power to vote or direct the vote: 1,676,200
                    (iii) Sole power to dispose or direct the disposition: -0-
                    (iv) Shared power to dispose or direct the disposition:
                    1,676,200

                    3. S.A.C. Capital Associates, LLC
                    (a) Amount beneficially owned: 1,640,600
                    (b) Percent of class: 1.3%
                    (c)(i) Sole power to vote or direct the vote: -0-
                    (ii) Shared power to vote or direct the vote: 1,640,600
                    (iii) Sole power to dispose or direct the disposition: -0-
                    (iv) Shared power to dispose or direct the disposition:
                    1,640,600


                                  Page 8 of 11





                    4. CR Intrinsic Investors, LLC
                    (a) Amount beneficially owned: 2,072,200
                    (b) Percent of class: 1.6%
                    (c) (i) Sole power to vote or direct the vote: -0-
                    (ii) Shared power to vote or direct the vote: 2,072,200
                    (iii) Sole power to dispose or direct the disposition: -0-
                    (iv) Shared power to dispose or direct the disposition:
                    2,072,200

                    5. Steven A. Cohen
                    (a) Amount beneficially owned: 3,748,400
                    (b) Percent of class: 3.0%
                    (c)(i) Sole power to vote or direct the vote: -0-
                    (ii) Shared power to vote or direct the vote: 3,748,400
                    (iii) Sole power to dispose or direct the disposition: -0-
                    (iv) Shared power to dispose or direct the disposition:
                    3,748,400

                    SAC Capital Advisors, SAC Capital Management, CR Intrinsic
                    Investors and Mr. Cohen own directly no Shares. Pursuant to
                    investment agreements, each of SAC Capital Advisors and SAC
                    Capital Management share all investment and voting power
                    with respect to the securities held by SAC Capital
                    Associates and SAC MultiQuant. Pursuant to an investment
                    management agreement, CR Intrinsic Investors has investment
                    and voting power with respect to the securities held by CR
                    Intrinsic Investments. Mr. Cohen controls each of SAC
                    Capital Advisors and SAC Capital Management. CR Intrinsic
                    Investments is a wholly owned subsidiary of SAC Capital
                    Associates. By reason of the provisions of Rule 13d-3 of the
                    Securities Exchange Act of 1934, as amended, each of (i) SAC
                    Capital Advisors, SAC Capital Management and Mr. Cohen may
                    be deemed to own beneficially 1,676,200 Shares (constituting
                    approximately 1.3% of the Shares outstanding) and (ii) CR
                    Intrinsic Investors and Mr. Cohen may be deemed to own
                    beneficially 2,072,200 Shares (constituting approximately
                    1.6% of the Shares outstanding). Each of SAC Capital
                    Advisors, SAC Capital Management, CR Intrinsic Investors and
                    Mr. Cohen disclaim beneficial ownership of any of the
                    securities covered by this statement, and SAC Capital
                    Associates disclaims beneficial ownership of any of the
                    securities held by CR Intrinsic Investments.


Item 5              Ownership of Five Percent or Less of a Class:
                    --------------------------------------------

                    If this statement is being filed to report the fact that as
                    of the date hereof the reporting person has ceased to be the
                    beneficial owner of more than five percent of the class of
                    securities, check the following. [X]

Item 6              Ownership of More than Five Percent on Behalf of Another
                    --------------------------------------------------------
                    Person:
                    ------

                    Not Applicable


                                  Page 9 of 11





Item 7              Identification and Classification of the
                    ----------------------------------------
                    Subsidiary Which Acquired the Security Being
                    --------------------------------------------
                    Reported on By the Parent Holding Company:
                    -----------------------------------------

                    Not Applicable

Item 8              Identification and Classification of Members
                    --------------------------------------------
                    of the Group:
                    ------------

                    Not Applicable

Item 9              Notice of Dissolution of Group:
                    ------------------------------

                    Not Applicable

Item 10             Certification:
                    -------------

     By signing below the signatory certifies that, to the best of his knowledge
and belief, the securities referred to above were not acquired and are not held
for the purpose of or with the effect of changing or influencing the control of
the issuer of the securities and were not acquired and are not held in
connection with or as a participant in any transaction having that purpose or
effect.


                                  Page 10 of 11





                                    SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.


Dated:  February 14, 2007

S.A.C. CAPITAL ADVISORS, LLC


By: /s/ Peter Nussbaum
   ---------------------------
Name:   Peter Nussbaum
Title:  Authorized Person


S.A.C. CAPITAL MANAGEMENT, LLC


By: /s/ Peter Nussbaum
   ---------------------------
Name:   Peter Nussbaum
Title:  Authorized Person


S.A.C. CAPITAL ASSOCIATES, LLC


By: /s/ Peter Nussbaum
   ---------------------------
Name:   Peter Nussbaum
Title:  Authorized Person


CR INTRINSIC INVESTORS, LLC


By: /s/ Peter Nussbaum
   ---------------------------
Name:   Peter Nussbaum
Title:  Authorized Person


STEVEN A. COHEN


By: /s/ Peter Nussbaum
   ---------------------------
Name:   Peter Nussbaum
Title:  Authorized Person


                                  Page 11 of 11