5. Charles and David Koch
Charles Koch is reported to possess more than $41 billion. The money he has accumulated throughout the years comes from a wide range of sources. Charles and David Koch took over a business from their father Fred Koch. Both sons have expanded their dad’s business since then. Originally their business was related to oil refining and chemicals. Now it covers a few other areas and includes commodity trading, fibers, polymers, pollution control technologies, ranching, minerals and fertilizers. Koch Industries is the second largest private corporation in the U.S. The brothers have recently performed business transactions – in 2014 they were also involved in acquiring Oplink, an optical network device company, for $445 million.