Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock, par value $0.01^F1,F2,F3	May 22, 2015	S	938,514	$36.60	D	22,654,372	I	See footnotes
Common Stock, par value $0.01^F4,F5,F6,F3	May 22, 2015	S	5,275,994	$36.80	D	17,378,378	I	See footnotes

Table II — derivative securities

No Table II lines on this filing.

Explanation of responses

F1Consists of 594,636 shares sold by Providence Equity Partners VI L.P. ("PEP VI"), 204,562 shares sold by Providence Equity Partners VI-A L.P. ("PEP VI-A") and 139,316 shares sold by PEP Co-Investors (CDW) L.P. ("PEP Co-Investor") to the Issuer in a stock repurchase.
F2Consists of 14,353,658 shares held directly by PEP VI, 4,937,831 shares held directly by PEP VI-A and 3,362,883 shares held directly by PEP Co-Investor. The shares held by PEP VI, PEP VI-A and PEP Co-Investor may be deemed to be beneficially owned by Providence Equity GP VI L.P. ("PEP GP"), the general partner of PEP VI, PEP VI-A and PEP Co-Investor and Providence Equity Partners VI L.L.C. ("PEP LLC"), the general partner of PEP GP. Messrs. Jonathan Nelson, Glenn Creamer and Paul Salem are members of PEP LLC and may be deemed to have shared voting and investment power over such shares. Each of PEP LLC, PEP GP, and Messrs. Nelson, Creamer and Salem hereby disclaims any beneficial ownership of any shares held by PEP VI, PEP VI-A and PEP Co-Investor except to the extent of any pecuniary interest therein.
F3Mr. Creamer has separately filed a Form 4.
F4Consists of 3,342,835 shares sold by PEP VI, 1,149,975 shares sold by PEP VI-A and 783,184 shares sold by PEP Co-Investor in an underwritten secondary offering.
F5This 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.
F6Consists of 11,010,823 shares held directly by PEP VI, 3,787,856 shares held directly by PEP VI-A and 2,579,699 shares held directly by PEP Co-Investor. The shares held by PEP VI, PEP VI-A and PEP Co-Investor may be deemed to be beneficially owned by PEP GP, the general partner of PEP VI, PEP VI-A and PEP Co-Investor and PEP LLC, the general partner of PEP GP. Messrs. Jonathan Nelson, Glenn Creamer and Paul Salem are members of PEP LLC and may be deemed to have shared voting and investment power over such shares. Each of PEP LLC, PEP GP, and Messrs. Nelson, Creamer and Salem hereby disclaims any beneficial ownership of any shares held by PEP VI, PEP VI-A and PEP Co-Investor except to the extent of any pecuniary interest therein.