Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
MULLER EDWARD R
  2. Issuer Name and Ticker or Trading Symbol
GenOn Energy, Inc. [GEN]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
Chairman, President and CEO
(Last)
(First)
(Middle)
1000 MAIN STREET
3. Date of Earliest Transaction (Month/Day/Year)
12/14/2012
(Street)

HOUSTON, TX 77002
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)
7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Stock 12/14/2012   F   11,708 (1) D $ 2.87 3,529,846 D  
Common Stock 12/14/2012   D   3,529,846 D (2) 0 D  
Common Stock 12/14/2012   D   1,190,573 D (2) 0 I By trust

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)
6. Date Exercisable and Expiration Date
(Month/Day/Year)
7. Title and Amount of Underlying Securities
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)
10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)
11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Stock Options $ 8.7 12/14/2012   D     1,150,567   (3) 01/13/2016 Common Stock 1,150,567 (3) 0 D  
Stock Options $ 8.84 12/14/2012   D     1,131,737   (4) 02/17/2016 Common Stock 1,131,737 (4) 0 D  
Stock Options $ 13.06 12/14/2012   D     370,653   (5) 03/07/2013 Common Stock 370,653 (5) 0 D  
Stock Options $ 3.67 12/14/2012   D     628,459   (6) 03/03/2019 Common Stock 628,459 (6) 0 D  
Stock Options $ 4.66 12/14/2012   D     571,473   (7) 03/11/2020 Common Stock 571,473 (7) 0 D  
Stock Options $ 3.81 12/14/2012   D     744,641   (8) 02/22/2011 Common Stock 744,641 (8) 0 D  
Stock Options $ 2.44 12/14/2012   D     1,166,823   (9) 02/26/2022 Common Stock 1,166,823 (9) 0 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
MULLER EDWARD R
1000 MAIN STREET
HOUSTON, TX 77002
  X     Chairman, President and CEO  

Signatures

 /s/ Edward R. Muller   12/18/2012
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) The reporting person disposed of these shares to satisfy tax withholding obligations related to the vesting of restricted stock units.
(2) The reporting person disposed of these shares in connection with the merger (the "Merger") involving GenOn Energy, Inc. and NRG Energy, Inc. in exchange for shares of NRG Energy, Inc. common stock, based on the exchange ratio of 0.1216 and having a market value of $23.00 per share on the effective date of the Merger, plus cash consideration for fractional shares.
(3) Upon completion of the Merger involving GenOn Energy, Inc. and NRG Energy, Inc., this fully-vested option was converted into an option to purchase 139,908 shares of NRG Energy, Inc. common stock at $71.55 per share.
(4) Upon completion of the Merger involving GenOn Energy, Inc. and NRG Energy, Inc., this fully-vested option was converted into an option to purchase 137,619 shares of NRG Energy, Inc. common stock at $72.70 per share.
(5) Upon completion of the Merger involving GenOn Energy, Inc. and NRG Energy, Inc., this fully-vested option was converted into an option to purchase 45,071 shares of NRG Energy, Inc. common stock at $107.41 per share.
(6) Upon completion of the Merger involving GenOn Energy, Inc. and NRG Energy, Inc., this fully-vested option was converted into an option to purchase 76,420 shares of NRG Energy, Inc. common stock at $30.19 per share.
(7) Upon completion of the Merger involving GenOn Energy, Inc. and NRG Energy, Inc., this fully-vested option was converted into an option to purchase 69,491 shares of NRG Energy, Inc. common stock at $38.33 per share.
(8) Upon completion of the Merger involving GenOn Energy, Inc. and NRG Energy, Inc., this fully-vested option was converted into an option to purchase 90,548 shares of NRG Energy, Inc. common stock at $31.34 per share.
(9) Upon completion of the Merger involving GenOn Energy, Inc. and NRG Energy, Inc., this option, which vests in three equal annual installments beginning February 27, 2013, was converted into an option to purchase 141,885 shares of NRG Energy, Inc. common stock at $20.07 per share.

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