CDW Corp — Director's Dealing 2014

May 30, 2014

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: CDW Corp (CDW)
CIK: 0001402057
Period of Report: 2014-05-28

Reporting Person: MADISON DEARBORN PARTNERS LLC (10% Owner)
Reporting Person: Madison Dearborn Capital Partners V - A L P (10% Owner)
Reporting Person: Madison Dearborn Capital Partners V - C L P (10% Owner)
Reporting Person: MADISON DEARBORN CAPITAL PARTNERS V EXECUTIVE-A L P (10% Owner)
Reporting Person: MDCP Co-Investors (CDW) LP (10% Owner)
Reporting Person: MADISON DEARBORN PARTNERS V-A&C, L.P. (10% Owner)
Reporting Person: MENCOFF SAMUEL M (10% Owner)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2014-05-28	Common Stock, par value $0.01	S	7730900	$28.35	Disposed	44598665	Indirect

Footnotes

F1: Consists of 5,046,479 shares sold by Madison Dearborn Capital Partners V-A, L.P. ("MDP A"), 1,338,743 shares sold by Madison Dearborn Capital Partners V-C, L.P. ("MDP C"), 50,707 shares sold by Madison Dearborn Capital Partners V Executive-A, L.P. ("MDP Exec") and 1,294,971 shares sold by MDCP Co-Investor (CDW), L.P. ("MDP Co-Investor").

F2: This sale price reflects the public offering price. The price received by the reporting persons will be reduced by the underwriter's commission of $0.15 per share.

F3: Consists of 29,112,548 shares held directly by MDP A, 7,723,056 shares held directly by MDP C, 292,523 shares held directly by MDP Exec and 7,470,538 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.

F4: 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.

F5: Mr. Finnegan has separately filed a Form 4.