U.S. stock market now in full run-up to Great Depression levels

• The Shiller CAPE ratio of 39-41 is more than double the historical average of 17 and has only been surpassed during the 2000 dot-com bubble peak
• Composite valuation measures now exceed 1929 pre-crash levels but remain slightly below the 2000 technology bubble peak, leaving little room for error in a market concentrated in AI-related mega-cap stocks
• Key risks include persistent inflation, higher interest rates increasing borrowing costs, AI spending potentially falling short of expectations, and growing U.S. fiscal challenges that could pressure valuations

Summary

Key Valuation Metrics:

U.S. stock market valuations have reached extreme levels, exceeding those seen before the 1929 crash that triggered the Great Depression. As of late May 2026, the Shiller CAPE ratio for the S&P 500 stands between 39 and 41—more than double its historical average of approximately 17. This reading has only been surpassed during the 2000 dot-com bubble peak.

Market Positioning:

Composite valuation measures combining the Shiller CAPE ratio, price-to-book value, and other long-term metrics now exceed pre-1929 levels, though remain slightly below 2000 dot-com bubble peaks. According to Bloomberg data, investors are paying historically high premiums for corporate earnings and assets despite economic and geopolitical uncertainty.

Drivers and Concentration Risk:

The rally has been primarily driven by a handful of AI-linked mega-cap technology giants with strong earnings. However, this concentration leaves the market vulnerable if AI spending disappoints expectations.

Historical Context:

Past valuation extremes resulted in severe corrections: the 1929 crash led to an 83% market decline, while the dot-com bust eliminated trillions in investor wealth.

Risk Factors:

Key threats include persistent inflation, higher interest rates increasing borrowing costs, global energy supply disruptions, stress in private credit markets, growing U.S. fiscal challenges, and softening employment trends from AI-driven efficiencies—all potentially weakening consumer spending and corporate valuations.

Counterbalancing Factors:

A downturn isn't inevitable. Strong earnings growth, AI-driven productivity gains, and resilient corporate balance sheets could continue supporting markets despite elevated valuations.