The company, which raised about $395 million, cut the number and price of shares earlier in the day, as U.S. stock markets remained volatile on concerns the U.S. Federal Reserve may roll back its stimulus policies.

The IPO priced at $17 per share.

The company reduced the number of shares in the IPO by 16 percent to 23.3 million and had lowered the expected price range to between $17 and $18 per share, from $20 to $23 per share.

This is because the company's private equity owners, Madison Dearborn LLC and Providence Equity Partners Inc, withdrew plans to sell a total of 4.5 million shares. The two firms took CDW private in 2007 for $7.3 billion.

CDW sells products from Apple Inc, Hewlett-Packard Co, International Business Machines Corp and others through its catalog and website.

The Dow Jones Industrial Average has declined more than 4 percent since it hit an all-time high a month ago after the Fed indicated it will stop the quantitative easing that has kept U.S. economy afloat.

U.S. industrial distribution company HD Supply, backed by Carlyle Group LP, Clayton, Dubilier & Rice LLC and Bain Capital LLC, raised $957.2 million, less than expected, in another IPO late on Wednesday.

JP Morgan, Barclays and Goldman Sachs are leading the offering from Vernon Hills, Illinois-based CDW, which plans to list its shares on Nasdaq under the symbol "CDW".