A new report from Wealth-X lists Wal-Mart heiress Christy Walton as the wealthiest woman in the world with an estimated net worth of $37.9 billion. Walton is closely followed by L'Oreal heiress Liliane Bettencourt, worth $31.3 billion. Collectively, the women on the Wealth-X list control US$114.6 billion of personal wealth. The youngest woman on the list is 33-year-old Yang Huiyan.