2. David Steward built his fortune running an IT service provider that counts Citi, Verizon, and the federal government as clients.

Net worth: $3.5 billion

Source of wealth: information technology services

Steward founded World Wide Technology, an IT services company that has generated over $11 billion in sales, according to Forbes. Steward, 68, serves as the company's chairman. The Missouri-based billionaire still has a majority stake in the company.