Microsoft had the world’s largest market capitalization at the close of the first trading day of 2000.
The software company entered the new millennium as the dominant listed business by market value. Its position reflected the importance of Windows and Office, the growth of personal computing, and investor enthusiasm during the late-1990s technology boom.
Market-cap rankings during that era were unusually volatile. Technology shares rose rapidly before the dot-com bubble burst, and several companies briefly approached or exceeded valuations associated with industrial leaders. Microsoft’s market value later fell sharply as technology stocks declined and regulators pursued an antitrust case against the company.
The wording “at the close” is important: an intraday ranking can differ from an end-of-day ranking because prices move throughout a trading session. Market capitalization also differs from revenue, profit, assets, or annual economic output.