Trump's Influence on US Stocks: Market Movements Driven by Policy, Strongest Impact in 40 Years

On April 24, Trump’s return to the White House has led to an unprecedented level of influence on the market. Data from Fundstrat shows that since January 2025, the five largest gain days and the five largest loss days in the US stock market have been directly driven by his policies, marking the first time in nearly 40 years that a single president has dominated extreme market fluctuations. Structurally, the gains are primarily due to technical rebounds following policy shocks: if the five strongest gain days are excluded, the S&P 500 would shift from an 18.5% increase since his inauguration to a 2.7% decrease. The losses are highly concentrated around tariff policy impacts. Analysts point out that Trump’s frequent adjustments to policy positions (escalation—easing—reversal), combined with the immediate signal release on social media, have led traders to shift towards ‘anticipating presidential intentions’ for trading, significantly weakening traditional macro frameworks.