Stocks rose on Wednesday after a tumultuous few days of trading following President Trump’s decision to impose tariffs on some of the United States’ biggest trading partners and retaliatory measures by the European Union, China and Canada.

Futures on the S&P 500, which allow investors to trade ahead of exchanges opening, were slightly higher. The Euro Stoxx 50 index, which comprises the eurozone’s largest listed companies, was up more than 1 percent in morning trading. Shares in Britain, Germany and France all broadly gained.

In Asia, stock markets in Japan, South Korea and Taiwan nudged higher. Those indices were seen as among the most exposed if President Trump broadened tariffs on longstanding trading partners. Hong Kong’s Hang Seng Index, a market that had been a bright spot in Asia, fell nearly 1 percent — a fourth straight day of decline.

As stock markets seemed to regain their footing on Wednesday, the European Union said it was implementing tariffs in retaliation to Mr. Trump’s 25 percent duty on steel and aluminum imports, which went into effect earlier in the day.

The European Commission called the U.S. tariffs on steel and aluminum “unjustified.” It said it would impose levies on a wide range of American goods that would take effect on April 1. Ursula von der Leyen, the president of the European Commission, said the tariffs were nearly equal in value to the metals duties being applied by the Trump administration.

The rise in stock prices reversed some of losses from earlier in the week and followed another turbulent trading day on Wall Street, after the White House introduced and then rolled back new tariffs. The whipsaw on tariffs has added to investors’ confusion over the Trump administration’s economic policy.