Microsoft became the world’s first publicly traded company valued above $500 billion in 1999.
Microsoft crossed the $500 billion market-capitalization threshold in December 1999, during the height of the dot-com-era technology boom. Investors placed enormous value on its dominant Windows operating system and rapidly expanding Office software business.
The milestone was based on the market value of Microsoft’s outstanding shares. It did not mean Microsoft held $500 billion in cash or generated that amount in annual sales. Technology valuations were especially high at the time, although many internet-related companies later suffered severe declines when the dot-com bubble burst.
Microsoft had gone public in 1986 and became one of the most influential software companies in personal computing. Its later businesses expanded into cloud services, gaming, enterprise software, professional networking, and artificial intelligence.