(Bloomberg) — There are many things that can move the stock market, from economic data to Federal Reserve announcements to corporate events. But for the past 15 months, traders’ fortunes have been largely tied to the moods of a single person: President Donald Trump.
Since taking office in January last year, Trump’s comments to reporters in impromptu Oval Office conversations and formal press conferences, in addition to his social media posts, have been the main driver behind the S&P 500 index’s five best and five worst days, according to an analysis by Fundstrat Research. It is unparalleled control among modern American leaders. No other president has orchestrated so many “best” and “worst” days over 12 terms, going back to Ronald Reagan in 1981.
“He has the market on a leash,” said Hardika Singh, economic strategist at Fundstrat. “The president should not have such an extraordinary degree of control over the fortunes of the stock market. It is completely unprecedented.”
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Biggest highs
The S&P 500’s five best days of Trump’s second term were driven by politics
The war in Iran provides the perfect backdrop to see how much Trump can move American stocks. The S&P 500 recently recorded its fastest V-shaped decline and recovery since 2020, plummeting 9% from its Jan. 27 peak to the brink of a technical correction on March 30, before resuming all-time highs over 11 trading sessions.
The impact of the president’s words becomes even clearer when looked at session by session. On March 20, for example, the S&P 500 fell 1.5% after Trump said, in a White House briefing, that he did not want a ceasefire with Iran. On March 31, the index rose 2.9%, in its best day since May, and continued to rise for the rest of the week, after Trump declared to several vehicles that negotiations with Iran were going well and that the war was close to an end. There are numerous similar examples before and after this period.
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And it’s not just stocks that have been moving. Commodity prices also swung wildly, with oil market volatility returning to levels last seen at the start of the Covid-19 pandemic.
In practice, Trump’s wavering stances on war have turned him into the market’s “arsonist and fireman,” said Alexander Altmann, head of tactical strategies in global equities at Barclays.
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The back-and-forth is strongly reminiscent of last year’s tariff-driven selloff and recovery, both linked to abrupt policy shocks from the president and undone by equally abrupt pullbacks. It has gotten to the point where Wall Street is anticipating changes in policy and rhetoric overnight.
“Investors have been conditioned — not wrongly — to expect that if things get really bad, especially if they’re government-induced… they’ll wait for the post saying, ‘Actually, everything’s fine,’” said Ross Mayfield, investment strategist at Baird Private Wealth Management.
The president’s influence over actions is not entirely new. Typically, the S&P 500’s biggest rises and falls are driven by a combination of micro and macro factors, and Washington politics is one of them. What sets Trump’s second term apart is the fact that market earnings track his social media posts and public appearances so closely.
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“I have never seen a market so affected by speeches coming out of the White House on a daily basis,” said veteran strategist Ed Yardeni of Yardeni Research. “Trump speaks every single day, and every single day he says something that seems to have an impact on the market.”
Trump’s fixation on stock prices as a kind of scoreboard was known before his second term began. Now, the White House’s official social media channels use their platforms to comment on market movements, releasing animations to celebrate S&P 500 records or asking Wall Street not to be “panic” when Trump’s words or policies raise fears. He even explicitly urged investors to buy shares.
“If we look again at the data, this has never happened before,” said Fundstrat’s Singh. “To me, that’s just insane.”
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Among the S&P 500’s best days in Trump’s current term are the 9.5% rise on April 9, 2025, when he lifted tariffs, and the 3.3% jump on May 12, 2025, when the U.S. and China agreed to a 90-day trade truce. On the opposite side, there is the 6% drop on April 4, 2025, after China retaliated with tariffs on the USA, and the 4.8% drop on April 3, 2025, after the president implemented broad tariffs for the first time.
Biggest falls
The S&P 500’s five worst days of Trump’s second term were driven by politics
Of course, some Wall Street professionals argue that the symbiosis between what the president says and what the market does is purely anecdotal and a result of the frequency with which he communicates.
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For example, an analysis of volatility measures contradicts the idea that the market has been more turbulent under Trump than under past administrations, said Barclays’ Altmann. The average value of the Cboe volatility index, the VIX, over each presidential term since the indicator’s creation in 1990 is 19.3 — exactly in line with Trump’s second term and Joe Biden’s term, according to Altmann’s analysis.
“While the world hangs on the president’s unorthodox communication methods and anticipates bouts of volatility as a consequence, the reality is that markets have behaved consistently with historical patterns,” Altmann said. “What has changed is the medium — high-frequency social media — through which the market reacts to news flow, not the magnitude of the reaction.”
The rise of passive investing has made the market more reactive to news in general, whether it’s comments from a CEO or surprising corporate earnings, said Michael Green, portfolio manager and chief strategist at Simplify Asset Management.
In simple terms, he explained, computers that manage passive portfolios are being programmed to buy or sell assets based on headlines, which drives movements in broader indices. By his estimate, markets are four to five times more reactive today than they have been historically.
“The volatility of headlines involving Trump just has to do with the fact that he speaks more frequently,” Green said. “The simple math is that he’s just a guy born in the right era.”
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