Donald Trump's Tariff Policy Has Repeatedly Triggered Multi-Trillion-Dollar Stock Swings Since Early 2025. Here's Why Markets Still Struggle to Price In His Next Move.

President Donald Trump is proving to be a very challenging commander-in-chief to work around for most investors, even as markets have soared during his tenure. On April 3, 2025, the day after the much-hyped "Liberation Day" barrage of new tariffs, the S&P 500 (SNPINDEX: ^GSPC) fell 4.8% as the Magnificent Seven group of technology companies corrected sharply downward.

Just six trading days later, most of the damage had been erased, leaving investors with whiplash and prompting many to wonder whether they'd sold their assets too hastily. Volatility never went away, but it now concentrates in individual stocks rather than the market as a whole. The gap between average single-stock volatility and index volatility hit an all-time high of 31% in early July 2026, according to CBOE Global Markets. Therein lies the crux of why markets are still struggling to get a read on what the president is going to do next.

Image source: The White House.

A single social media post from Trump vaporized $2 trillion of market value in one day

U.S. tariff policy has changed more than 50 times since January 2025, according to the Tax Foundation. In most of those cases, investors learned about the policy changes via a social media post from the president. The market's moves with each new change have frequently rivaled past stock market crashes in size.

For instance, Nike crashed 14% on April 3, 2025, and Apple declined by 9%. Both crashes were caused by the companies' heavy reliance on supply chains in Asia, which were hit by the new tariffs. Then, on April 9, 2025, Trump waived the initially declared tariff rates for 90 days, causing Apple to bounce by 15.3%. The S&P 500 itself had its best day since 2008.

Months afterward, on Oct. 10, the president threatened a large tariff increase on Chinese goods, then set a new 100% tariff rate to take effect on Nov. 1. Roughly $2 trillion of American stock market value vanished that afternoon. Three weeks later, after a high-profile meeting with Chinese President Xi Jinping, the increases were scrapped.

Adaptation is extremely difficult here

The market is caught in a pickle regarding the Trump administration's chaotic approach to announcing and implementing new trade policies.

The president's statements cannot be taken literally, nor can they be taken as predictive of the policies that will actually be implemented. Given the nature of trade policy negotiations, his public statements must be considered part of a bargaining process. Tariffs can also be waived for some or all of the affected stakeholders. Apple won an exemption from the 100% semiconductor tariff in August 2025.

At the same time, the market can't ignore or fully discount the administration's statements. Haphazard as the tariff policies may be, the president is the head of government, and the government thus reacts to his dictates, even if they're ill-advised or contradictory.

This is the reason for the volatility. The market has no choice but to believe today that Trump's preferences will translate into real policy, even though it might not.

So far, it looks like the best approach for investors is to take advantage of downside volatility when it arrives, and load up on quality names when they're valued at a panic discount.

Alex Carchidi has positions in Apple. The Motley Fool has positions in and recommends Apple and Nike. The Motley Fool has a disclosure policy.