Microsoft Surges 16% as AI Earnings Reports Spark Market Stampede

The week of July 28 to 31, 2026, saw a significant market response to AI, as the five largest tech firms released their earnings reports. Microsoft's Q4 FY2026 earnings after the close on July 29 led to a 16% stock spike, adding $450 billion to its market capitalization in a single day. This made it the most significant single-day market capitalization increase in stock market history.

The rally triggered a stampede on the broad market, with the S&P 500 up 1.7%, the Nasdaq up 2.8%, and an 8% gain in the iShares Semiconductor ETF. Amazon's after-hours report also saw its stock gain 10%, marking a 37% increase in AWS, which is Amazon's fastest growth since 2021.

However, Meta's earnings report miss resulted in a 14% decline in earnings per share, and free cash flow decreased to $784 million, causing a 9.64% decline in Meta stock. Apple's stock decreased by 3-4%, despite reporting record earnings for the month of June.

The KOSPI saw its largest one-day increase ever, with a total increase of 17.91%. The underlying mechanisms behind these events suggest that companies can win by demonstrating demand before spending on capex. Microsoft and Amazon showed this pattern, while Meta and Alphabet showed the opposite case.