Walmart's Walton family has topped Bloomberg's list of the world's 25 richest families with $238.2 billion in wealth. It's followed by confectionery company Mars' owners with $141.9 billion in wealth, Koch family of Koch Industries at $124.4 billion, the family behind Hermès at $111.6 billion and Saudi royal family at $100 billion. Mukesh Ambani's family ranks sixth with $93.7 billion.