New York. US stocks fell Wednesday after Nvidia warned new restrictions on exports to China will chisel billions of dollars off its results, while companies around the world said President Donald Trump’s trade war is clouding forecasts for how they and the economy will do this year.

The S&P 500 sank 2.2 percent after falling as much as 3.3 percent earlier. Such an amount would have vied for one of its worst losses in years before the historic, chaotic swings that have upended Wall Street in recent weeks.

The Dow Jones Industrial Average dropped 699 points, or 1.7 percent and the Nasdaq composite sank a market-leading 3.1 percent.

Losses accelerated after the head of the Federal Reserve said again that Trump’s tariffs appear to be bigger than it expected, which could in turn slow the economy and raise inflation more than it had earlier thought. But Jerome Powell also said again that the Fed will need more time before deciding whether to lower interest rates, which could help the economy but make inflation worse, or to do the opposite.

“All of this is highly uncertain,” Powell said. “We’re thinking now, really before the tariffs have their effects, (about) how they might affect the economy. That’s why we’re waiting really to see what the policies ultimately are, and then we can make a better assessment of what the economic effects will be.”

Some companies are already seeing big effects because of changes in Washington.

Nvidia dropped 6.9 percent after it said the US government is restricting exports of its H20 chips to China, citing worries that they could be used to build a supercomputer. The restrictions could mean a hit of $5.5 billion to Nvidia’s results for the first quarter, covering charges related to inventory and purchase commitments.

Advanced Micro Devices sank 7.3 percent after it said US limits on exports to China for its own chips may mean a hit of up to $800 million for inventory and other charges.

In Amsterdam, ASML’s stock sank 5.2 percent. The Dutch company, whose machinery makes chips, said demand for artificial intelligence technology is continuing to drive growth. “However, the recent tariff announcements have increased uncertainty in the macro environment and the situation will remain dynamic for a while,” CEO Christophe Fouquet said.

The uncertainty around Trump’s trade war has been scrambling plans for companies across industries and around the world. It’s so dynamic that United Airlines gave two different financial forecasts for how it may perform this year, one if there’s a recession and one if not.

The airline said it made the unusual move to give twin forecasts because it believes it’s “impossible to predict this year with any degree of confidence.”

United’s stock finished roughly flat even though it reported a stronger profit for the latest quarter than analysts expected.

Many investors are bracing for a possible recession because of Trump’s tariffs, which he has said he hopes will bring manufacturing jobs back to the United States and trim how much more it imports from other countries than it exports. A survey of global fund managers by Bank of America found expectations for recession are at the fourth-highest level in the last 20 years.

The World Trade Organization said Wednesday it expects tariffs to cause a 0.2 percent decline in the volume of world merchandise trade for 2025. That’s if the tariff situation remains as it was on Monday. Trade could shrink by 1.5 percent this year if conditions worsen, the WTO said.

The “enduring uncertainty threatens to act as a brake on global growth, with severe negative consequences for the world, the most vulnerable economies in particular,” Director-General Ngozi Okonjo-Iweala said.

One US company that moves products around the continent, J.B. Hunt Transport Services, tumbled 7.7 percent for one of Wall Street’s sharper losses, even though it reported slightly stronger profit for the latest quarter than analysts expected.

All told, the S&P 500 fell 120.93 points to 5,275.70. The Dow Jones Industrial Average dropped 699.57 to 39,669.39, and the Nasdaq composite sank 516.01 to 16,307.16.

Tariffs could also drive up inflation, at least temporarily, by pushing US importers to pass along the higher costs to their customers.

Fears about such price hikes drove a spending binge last month, and sales at US retailers accelerated by more than economists expected. Economists said much of that was likely because of US shoppers rushing to buy automobiles, electronics and other items before their prices could rise due to possible tariffs.

Recent surveys have shown US households are feeling more pessimistic about the economy because of tariffs, and fear is that it could lead them to pull back on their spending eventually, which could cause a recession by itself.