The American stock market tumbled today to its lowest point in several months. The S&P 500 dropped 2.7 percent, its worst single-day decline of the year. And the tech-heavy Nasdaq slipped 4 percent, fueled in part by sharp drops in the stock prices of some of the U.S.’s most valuable companies — like Tesla, which fell by more than 15 percent.

By most measures, the U.S. economy is still in good shape. But as stocks have recoiled over the past three weeks, many economists’ predictions have turned gloomier.

Analysts we spoke to said the economic angst was in part a result of the uncertainty around tariffs. Over the last few weeks, President Trump has threatened, imposed, suspended and resumed levies on America’s three largest trade partners. Today, retaliatory tariffs by China on U.S. agricultural products came into effect. And later this week, the Trump administration is set to put in place a 25 percent tariff on all U.S. steel and aluminum imports.

When Trump was asked this weekend about an economic slowdown, he acknowledged that there could be “a period of transition.” He declined to rule out the possibility of a recession, and instead insisted that, in the long run, his policies would bring “wealth back to America.”

Secretary of State Marco Rubio, today, on a plane headed for Jeddah, Saudi Arabia.Credit…Pool photo by Saul Loeb

Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.

Thank you for your patience while we verify access.

Already a subscriber? Log in.

Want all of The Times? Subscribe.