In 2007, Midwestern private equity firm Madison Dearborn Partners paid $7.3 billion for Illinois based computer reseller CDW. Continuing to buy up the neighborhood, Madison Dearborn followed up its buyout later that year by paying $5.75 billion for the Chicago-based investment house Nuveen Investments. Madison Dearborn paid $87.75 in cash per share for the CDW, seller of computers, hardware and office equipment to business customers, a 16% premium over the trading price of shares prior to its announcement. According to company filings, sales have increased over 8% year over year and overall operating income is up 30%. The company has not yet filed for an I.P.O. with the SEC and has $4.2 billion in debt.