The Shiller P/E Ratio of the US Stock Market Reaches a 25-Year Extreme Level, AI Frenzy Sparks Concerns of a Reprise of the 'Internet Bubble'

BlockBeats News, May 23rd. Data shows that the 2026 Shiller P/E ratio of the U.S. stock market has risen to a range of approximately 39.5 to 41.7, the highest level in the past 25 years, only below the about 44 times during the peak of the 1999 Internet bubble.

Analysis points out that the surge in valuation in this round is mainly driven by the AI concept, including the continuous rise of tech giants in the semiconductor, cloud computing, and AI infrastructure sectors. A few large-cap tech stocks have accounted for most of the S&P 500's gains. The market is concerned that the current trend bears similarities to the 1999 Internet bubble.

However, the report believes that unlike the large number of unprofitable Internet companies back then, today's AI industry leaders generally have strong cash flow, mature business models, and high-profit margins, providing a stronger fundamental support. The current AI investment frenzy has expanded into data centers, energy, the power grid, and enterprise-level AI applications.

Analysts warn that the current market is highly concentrated on a few AI giants. If interest rates rise in the future, AI commercialization falls short of expectations, or profit growth slows down, the U.S. stock market still faces valuation compression and volatility risks. Historical data shows that after the Shiller P/E ratio enters a historically high range, the actual return on the U.S. stock market over the next decade usually tends to be low single digits.