Microsoft developed Azure and Windows and briefly became the world’s most valuable public company in 1999. Its market capitalization reached roughly $618.9 billion during the dot-com-era stock boom, a record at the time.
Microsoft was founded by Bill Gates and Paul Allen in 1975. The company first became widely dominant through operating-system software licensed to computer manufacturers, especially MS-DOS and Windows. Its Office productivity suite later became another major business.
Azure, launched commercially in 2010, gave Microsoft a major position in cloud computing. Under CEO Satya Nadella, cloud services became central to the company’s strategy and helped renew investor interest in Microsoft.
The 1999 peak should not be confused with Microsoft’s later market-value leadership. Companies can move up or down in rankings as share prices change, so a historical title is not a permanent ranking.