Microsoft briefly surpassed Apple as the world’s most valuable publicly traded company in November 2018.
On November 30, 2018, Microsoft’s market capitalization moved above Apple’s during trading. The change reflected both companies’ share-price movements rather than a formal change in ownership or a permanent ranking. Market-cap rankings can change quickly because they are based on publicly traded share prices.
Microsoft’s rise was associated with strong growth in cloud computing, especially Azure, along with enterprise software and subscription products such as Microsoft 365. Apple, meanwhile, remained one of the largest companies in the world through the strength of its iPhone, services, and hardware businesses.
Microsoft and Apple have repeatedly exchanged the top position in later years. This makes the date important: the question concerns a brief market-cap crossover in 2018, not the company that held the ranking permanently.