Sec Form 4 Filing - FINNEGAN PAUL J @ CDW Corp - 2015-05-22

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 FINNEGAN PAUL J 2. Issuer Name and Ticker or Trading Symbol CDW Corp [ CDW] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O MADISON DEARBORN PARTNERS, LLC, 70 W. MADISON STREET, SUITE 4600 3. Date of Earliest Transaction (MM/DD/YY) 05/22/2015 (Street) CHICAGO, IL60602 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, par value $0.01 05/22/2015 S 1,061,486 ( 1 ) D $ 36.6 25,622,779 ( 2 ) I See footnotes ( 2 ) ( 3 ) ( 4 ) Common Stock, par value $0.01 05/22/2015 S 5,967,310 ( 5 ) D $ 36.8 ( 6 ) 19,655,469 ( 7 ) I See footnotes ( 3 ) ( 4 ) ( 7 )

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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other FINNEGAN PAUL J C/O MADISON DEARBORN PARTNERS, LLC 70 W. MADISON STREET, SUITE 4600 CHICAGO, IL60602 X X Signatures /s/ James S. Rowe, under Power of Attorney 05/27/2015 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Consists of 692,904 shares sold by Madison Dearborn Capital Partners V-A, L.P. ("MDP A"), 183,815 shares sold by Madison Dearborn Capital Partners V-C, L.P. ("MDP C"), 6,962 shares sold by Madison Dearborn Capital Partners V Executive-A, L.P. ("MDP Exec") and 177,805 shares sold by MDCP Co-Investor (CDW), L.P. ("MDP Co-Investor") to the Issuer in a stock repurchase. ( 2 )Consists of 16,725,710 shares held directly by MDP A, 4,437,042 shares held directly by MDP C, 168,061 shares held directly by MDP Exec and 4,291,966 shares held directly by MDCP Co-Investor. Madison Dearborn Partners V-A&C, L.P. (''MDP V'') is the general partner of MDP A, MDP C, MDP Exec and MDP Co-Investor. Madison Dearborn Partners, LLC (''MDP'') is the general partner of MDP V. As the sole members of a limited partner committee of MDP V that has the power, acting by majority vote, to vote or dispose of the shares directly held by MDP A, MDP C, MDP Exec and MDP Co-Investor, Paul J. Finnegan and Samuel M. Mencoff may be deemed to have shared voting and investment power over such shares. Each of Messrs. Finnegan and Mencoff and MDP V hereby disclaims any beneficial ownership of any shares held by MDP A, MDP C, MDP Exec and MDP Co-Investor except to the extent of its or his pecuniary interest therein. ( 3 )Mr. Mencoff has an indirect pecuniary interest in the shares of CDW Corporation's common stock held of record by the various MDP funds described above through his investment in MDP V. Each of MDP A, MDP C, MDP Exec and MDP Co-Investor and Mr. Mencoff may be deemed to share beneficial ownership of the reported securities and expressly disclaims beneficial ownership of such shares except to the extent of its or his pecuniary interest therein. ( 4 )The record and other beneficial beneficial owners of the reported securities have separately filed a Form 4. ( 5 )Consists of 3,895,264 shares sold by MDP A, 1,033,346 shares sold by MDP C, 39,140 shares sold by MDP Exec and 999,560 shares sold by MDP Co-Investor in an underwritten secondary offering. ( 6 )This sale price reflects the public offering price. The price received by the reporting persons will be reduced by the underwriters' commission of $0.20 per share. ( 7 )Consists of 12,830,446 shares held directly by MDP A, 3,403,696 shares held directly by MDP C, 128,921 shares held directly by MDP Exec and 3,292,406 shares held directly by MDCP Co-Investor. MDP V is the general partner of MDP A, MDP C, MDP Exec and MDP Co-Investor. MDP is the general partner of MDP V. As the sole members of a limited partner committee of MDP V that has the power, acting by majority vote, to vote or dispose of the shares directly held by MDP A, MDP C, MDP Exec and MDP Co-Investor, Paul J. Finnegan and Samuel M. Mencoff may be deemed to have shared voting and investment power over such shares. Each of Messrs. Finnegan and Mencoff and MDP V hereby disclaims any beneficial ownership of any shares held by MDP A, MDP C, MDP Exec and MDP Co-Investor except to the extent of its or his pecuniary interest therein.

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

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