Historical Trends Suggest 2026 Stock Rally May Stall Despite AI Optimism

New York, Friday, 9 January 2026.
As the S&P 500 enters the fourth year of its bull run—which began in October 2022—investors face a critical historical divergence. While Deutsche Bank forecasts the index reaching 8,000 by year-end driven by a projected $440 billion in Big Tech AI spending, historical data signals imminent headwinds. StoneX analysis reveals that since the 1940s, the fourth year of a bull market has never delivered double-digit returns, typically resulting in a pause rather than a crash. With the top 10 stocks now comprising 40% of the index—a concentration unseen since the 1960s—and valuations at peak levels, the market is testing the limits of historical precedent. Investors must weigh the momentum of the AI semiconductor boom against data indicating that only two of the last six bull markets survived past 51 months.