Sec Form 4 Filing - DeFontes Kenneth William Jr. @ EXELON CORP - 2012-08-03

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 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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1. Name and Address of Reporting Person DeFontes Kenneth William Jr. 2. Issuer Name and Ticker or Trading Symbol EXELON CORP [ EXC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) President & CEO, BGE (Last) (First) (Middle) 10 SOUTH DEARBORN STREET, 54TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 08/03/2012 (Street) CHICAGO, IL60603 4. If Amendment, Date Original Filed (MM/DD/YY) 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 (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 08/03/2012 M( 1 ) 7,500 A $ 21.25 17,691 ( 4 ) D Common Stock 08/03/2012 S( 1 ) 7,500 A $ 38.33 10,191 D Common Stock - Restricted Stock Units 9,668 ( 5 ) ( 6 ) D Common Stock- 401k Plan Shares 7,971 ( 2 ) I by 401k Plan Common Stock 11,777 ( 7 ) I Held by Spouse

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 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 NQ Stock Options 02/27/2009 $ 21.25 08/03/2012 M( 1 ) 7,500 ( 3 ) ( 3 ) Common Stock 7,500 ( 3 ) 76,330 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other DeFontes Kenneth William Jr. 10 SOUTH DEARBORN STREET 54TH FLOOR CHICAGO, IL60603 President & CEO, BGE Signatures Lawrence C. Bachman, Attorney in Fact for Kenneth W. DeFontes, Jr. 08/03/2012 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Exercise and all reported sales made pursuant to a rule 10b5-1 trading plan entered into on June 13, 2012. ( 2 )Common stock as of 07/31/2012 held in a multi-fund 401(k) plan. ( 3 )Non qualified employee stock options originally granted pursuant to the Constellation Energy Group Long Term Incentive Plan. Each Constellation option was converted from the right to purchase 1 share of Constellation common stock to the right to purchase 0.93 shares of Exelon common at a strike price equal to the quotient of the original Constellation strike price and 0.93. This grant became fully vested upon conversion on March 12, 2012. Options expire 10 years from the grant date referenced in Column 1. ( 4 )Balance includes 103 shares acquired on 06/08/2012 through automatic dividend reinvestment. ( 5 )Restricted stock units originally granted pursuant to the Constellation Energy Group Long Term Incentive Plan and each stock unit was converted to 0.93 stock units of Exelon Corporation on March 12, 2012. Stock units will settle in shares of Exelon common stock on a 1 for 1 basis upon vesting. Award will vest 1/3 in February 2013, 1/3 in February 2014 and 1/3 in February 2015. ( 6 )Balance includes 97 shares aquired on 06/08/2012 through automatic dividend reinvestment. ( 7 )Balance inlcudes 119 shares acquired on 06/08/2012 through automatic dividend reinvestment.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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