58. CHRISTY WALTON

$8.5

BILLION  SELF-MADE SCORE: ! SOURCE: WALMART AGE: 70 RESIDENCE: JACKSON, WY PHILANTHROPY SCORE: When her husband, John, son of Walmart founder Sam Walton, died in a plane crash in 2005, she inherited a stake in the retailer, but most of her late husband’s shares went to their only child, Lukas (No. 28). In 2010 she established Cuna del Mar, an investment fund focused on creating a sustainable supply of seafood.