Other notable members are Oracle's Larry Ellison at no. 3; Jim and Alice Walton of Walmart at seven and eight (separated by a mere $100 million); and New York City mayor Michael Bloomberg rounds out the top 10 with $18 billion.
Notably tied for fifth place with $21.5 billion are Charles and David Koch. The New Yorker pegged David Koch as one of the major forces behind the tea party movement in a recent issue.
Forbes reports that the methodology behind the list is based on "our reporters meet[ing] with the list candidates and their handlers and interview employees, rivals, attorneys, ex-spouses and securities analysts. We keep track of their moves: the deals they negotiate, the land they're selling, the paintings they're buying, the causes they give to."