X0306 4 2014-03-12 0 0001402057 CDW Corp CDW 0001576839 TROKA MATTHEW A. C/O CDW CORPORATION 200 N. MILWAUKEE AVE VERNON HILLS IL 60061 0 1 0 0 See Remarks Common Stock, par value $0.01 2014-03-12 4 S 0 26204 25.55 D 237913 D Represents shares of CDW Corporation common stock sold in an underwritten secondary offering. This sale price reflects the public offering price. The price received by the reporting person will be reduced by the underwriter's commission of $0.25 per share. Senior Vice President-Product and Partner Management /s/ James S. Rowe, under Power of Attorney 2014-03-13