Is a Stock Market Crash Likely Under President Donald Trump? History Weighs In With an Answer Wall Street May Not Like.

The relationship between Donald Trump's presidency and outsize stock market returns has been a topic of discussion. While some Wall Street catalysts have developed organically, such as advancements in artificial intelligence, the Trump administration's policies have also contributed to the bull market rally. The Tax Cuts and Jobs Act, signed into law in December 2017, lowered the peak marginal corporate income tax rate to 21%, which led to a surge in buyback activity from S&P 500 companies.

Despite the current surging highs of the Dow Jones Industrial Average, S&P 500, and Nasdaq Composite, there are historical indications that the Trump bull market may be nearing an end.

Two historical precedents offer insights into the likelihood of a stock market crash under President Trump. Firstly, premium stock valuations, measured by the S&P 500's Shiller Price-to-Earnings (P/E) Ratio, have reached historically high levels. When the Shiller P/E Ratio surpasses 30, bear market declines have followed in five out of six instances over the past 156 years.

Currently, the Shiller P/E Ratio is near its all-time high of 44.19, suggesting a significant risk of a market correction. Secondly, outstanding margin debt has surged to unprecedented levels, reaching $1.502 trillion over 14 months as of June 2026. Parabolic increases in margin debt have historically signaled the end of long-winded bull markets, as seen in the dot-com bubble burst and the financial crisis.

While these historical precedents suggest that the likelihood of a stock market crash under President Trump is increasing, the pendulum of history has a tendency to favor optimism. With a disproportionate amount of time favoring bullish market conditions, there is still a possibility that the current market rally may continue. Nonetheless, the historical evidence indicates that significant downside events, potentially including crashes, have been a recurring theme in stock market history.