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 * ALLEN PAUL J   2. Issuer Name and Ticker or Trading Symbol CONSTELLATION ENERGY GROUP INC [CEG] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Senior Vice President (Last) (First) (Middle) 100 CONSTELLATION WAY 3. Date of Earliest Transaction (Month/Day/Year) 03/12/2012 (Street) BALTIMORE, MD 21202 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 03/12/2012   D   11,741.728 D (1) 0 D   Common Stock 03/12/2012   D   1,887.1387 D (1) 0 I By 401 (k)

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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 (right to buy) (2)	$ 28.81	03/12/2012		D			23,290	(3)	05/02/2013	Common Stock	23,290	(3)	0	D
Stock options (right to buy) (2)	$ 39.63	03/12/2012		D			18,190	(4)	02/26/2014	Common Stock	18,190	(4)	0	D
Stock options (right to buy) (2)	$ 50.96	03/12/2012		D			18,680	(5)	02/24/2015	Common Stock	18,860	(5)	0	D
Stock options (right to buy) (2)	$ 75.85	03/12/2012		D			12,090	(6)	02/22/2017	Common Stock	12,090	(6)	0	D
Stock options (right to buy) (2)	$ 93.97	03/12/2012		D			9,330	(7)	02/21/2018	Common Stock	9,330	(7)	0	D
Stock options (right to buy) (2)	$ 19.76	03/12/2012		D			36,060	(8)	02/27/2019	Common Stock	36,060	(8)	0	D
Stock options (right to buy) (2)	$ 35.07	03/12/2012		D			21,710	(9)	02/26/2020	Common Stock	21,710	(9)	0	D
Stock options (right to buy) (2)	$ 30.18	03/12/2012		D			31,790	(10)	02/25/2021	Common Stock	31,790	(10)	0	D
Stock options (right to buy) (2)	$ 36.49	03/12/2012		D			39,530	(11)	02/24/2022	Common Stock	39,530	(11)	0	D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
ALLEN PAUL J 100 CONSTELLATION WAY BALTIMORE, MD 21202			Senior Vice President

Signatures

Sean J. Klein, Attorney-In-Fact		03/14/2012
**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)	Disposition of common stock pursuant to Agreement and Plan of Merger (the "Merger") between Exelon Corporation ("Exelon"), Bolt Acquisition Corporation, and Constellation Energy Group, Inc. ("Constellation"), whereby each share of Constellation common stock, without par value, converted into the right to receive 0.9300 shares of Exelon common stock, without par value, having a closing market value of $39.81 per share on the effective date of the Merger and a cash payment being made for any fractional shares.
(2)	These are employee stock options.
(3)	Pursuant to the Merger, each Constellation stock option vested and converted into an option to purchase 0.9300 shares of Exelon common stock, without par value, at an exercise price of $30.98 per share.
(4)	Pursuant to the Merger, each Constellation stock option vested and converted into an option to purchase 0.9300 shares of Exelon common stock, without par value, at an exercise price of $42.62 per share.
(5)	Pursuant to the Merger, each Constellation stock option vested and converted into an option to purchase 0.9300 shares of Exelon common stock, without par value, at an exercise price of $54.80 per share.
(6)	Pursuant to the Merger, each Constellation stock option vested and converted into an option to purchase 0.9300 shares of Exelon common stock, without par value, at an exercise price of $81.56 per share.
(7)	Pursuant to the Merger, each Constellation stock option vested and converted into an option to purchase 0.9300 shares of Exelon common stock, without par value, at an exercise price of $101.05 per share.
(8)	Pursuant to the Merger, each Constellation stock option vested and converted into an option to purchase 0.9300 shares of Exelon common stock, without par value, at an exercise price of $21.25 per share.
(9)	Pursuant to the Merger, each Constellation stock option vested and converted into an option to purchase 0.9300 shares of Exelon common stock, without par value, at an exercise price of $37.71 per share.
(10)	Pursuant to the Merger, each Constellation stock option vested and converted into an option to purchase 0.9300 shares of Exelon common stock, without par value, at an exercise price of $32.46 per share.
(11)	Pursuant to the Merger, each Constellation stock option converted into an option to purchase 0.9300 shares of Exelon common stock, without par value, at an exercise price of $39.24 per share. These stock options were granted on 2/24/12 and will vest on 2/24/13, 2/24/14, and 2/24/15.

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