From the IBM article on Wikipedia: (emphasis mine)

IBM has often been described as having a sales-centric or a sales-oriented business culture. Traditionally, many IBM executives and general managers are chosen from sales force. The current CEO, Samuel J. Palmisano, for example, joined the company as a salesman and, unusual for CEOs of major corporations, has no MBA or post-graduate qualification. Middle and top management are often enlisted to give direct support to salesmen when pitching sales to important customers.