$22.5 billion

Walmart. U.S.

World’s largest retailer benefited as cash-strapped shoppers looked to discount merchandise at start of economic slump. Boost may have waned; recently reported 1.6% decline in same-store sales in its U.S. Walmart and Sam’s Club stores, warned of soft sales in current quarter. Still, shares are up 7% in past 12 months and family fortune rose a combined $13 billion, largely recovering losses from market crash. Sam Walton started as J.C. Penney clerk. Opened Benjamin Franklin five-and-dime in 1945; lost lease five years later. Founded Bentonville, Ark., general store with brother James in 1962. Today Walmart has $405 billion in annual sales, 2 million employees, more than 8,400 stores. Christy is the richest of the Waltons thanks to late husband John’s early bet on First Solar; alternative energy stock up more than 350% since 2006 public offering.