A previous version of this report misstated the wealthiest woman on the list. The report has been corrected.

Elizabeth Holmes, founder of Theranos, is the wealthiest U.S. woman on the list. Getty Images

The richest 30-year-old on the planet has five times the net worth of the second wealthiest person under 40. It won’t come as a surprise that he — and three other people on the list — do or did work at Facebook.