Microsoft became the first company to reach a US$500 billion market capitalization during the dot-com era.
Microsoft crossed a US$500 billion market value in 1999, during the late-1990s technology boom. Investors placed a high valuation on the company because its Windows operating system dominated personal computers and Microsoft Office had become a standard productivity suite.
The company’s market value reflected expectations about future earnings as well as its existing business. The same period produced very high valuations for other technology companies, but many dot-com firms later suffered severe declines when the technology bubble burst in 2000.
Historical market-cap records can be difficult to compare because companies split their shares, buy back stock, or issue new shares. Market capitalization adjusts for those changes, while a share price alone does not. Microsoft’s record therefore refers to the total value of its equity, not to a single share’s price.