Bill Gates was 31 when he became a billionaire. Microsoft’s 1986 initial public offering made shares in the company publicly tradable, and a sharp rise in Microsoft’s stock price soon pushed Gates’ personal wealth above the billion-dollar mark.
In 1987, Forbes listed Gates as the world’s youngest billionaire. His fortune was tied primarily to his ownership of Microsoft, the software company he co-founded with Paul Allen in 1975 after leaving Harvard. Microsoft’s success with operating systems and business software made its founders extraordinarily wealthy as personal-computer use expanded.
The milestone is sometimes confused with Gates becoming the world’s richest person. That happened later: Forbes ranked him the wealthiest person in the world for many years, including a continuous run from 1995 through 2007. Gates also became the first centibillionaire in 1999, when his net worth briefly exceeded $100 billion.
The key date is therefore 1987, when Gates was 31—not the 1970s, when Microsoft was founded, or 1986, the year of the IPO itself.