Abigail Johnson (U.S.) $11.5 billion

48. Married, 2 children

With her father she controls Fidelity Investments, America's largest mutual fund company, founded by her grandfather. She earned an MBA at Harvard and joined the family business in 1988. Abby got to run her first diversified fund at age 28. Now she runs personal and workplace investing division; believed by some to be father's chosen successor.