CDW provides technology products and services—from hardware to security systems to cloud computing—for businesses, schools, and the government. Founded in 1984, the company emerged from a $3 Chicago Tribune classified advertisement to sell a used computer in 1982. CDW was publicly traded from 1993 until 2007 (when it went private in a $7.3 billion deal by Madison Dearborn Partners and Providence Equity Partners) and it made its Fortune 500 debut in 2001 at No. 435. Today the Illinois company is public once again, thanks to a 2013 IPO on the Nasdaq, and counts more than 10,000 employees and 250,000 customers.