Microsoft’s 1986 initial public offering made Bill Gates a billionaire.
Microsoft went public on March 13, 1986, offering shares at US$21 each. The flotation valued the software company at roughly US$350 million at the time, but the stock rose sharply during its first day of trading. Gates owned a large portion of Microsoft, so the increase made him a billionaire at age 30.
The company had been founded in 1975 by Gates and Paul Allen. Microsoft first became widely known for supplying the MS-DOS operating system used by IBM-compatible personal computers. It later built a dominant position with Windows, Office, developer tools, cloud services, and enterprise software.
This fact concerns personal wealth created by ownership, not Microsoft’s market capitalization itself. Market capitalization changes whenever a public company’s share price changes, while a founder’s wealth also depends on the number of shares retained and other assets. Microsoft eventually became one of the world’s most valuable listed companies, alongside Apple, Alphabet, Amazon, and Nvidia.