U.S. stock markets started off trading Thursday by taking a significant tumble after President Donald Trump announced worldwide tariffs that will likely be met with retaliatory measures from countries around the globe.

Both the S&P 500 and the Dow Jones Industrial Average opened about 3% lower than their closing values on Wednesday. As of early Thursday morning, the S&P 500 had lost about 6% of its value over the last month, while the Dow Jones Industrial Average had decreased by about 5% during the same period.

Numerous sectors experienced significant drops. Restoration Hardware, Five Below, and Wayfair were the companies with the biggest losses as of Thursday morning. Other major corporations such as Dollar Tree, Nike, and Target also suffered significant losses.

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Gary Friedman, CEO of Restoration Hardware, told investors on Thursday that he did not think President Trump would stick with the tariffs.

"I think it’s just a little shocking because we’ve never seen an administration and a leader like Trump," he said. "I mean, it’s impressive, quite frankly. You know, usually governments move like glaciers, and he’s the opposite. Exactly how it’s gonna play out, I don’t know. I don’t think it’s time to overreact."

However, leaders of other companies have voiced concern that tariffs would cause prices to increase and hurt consumers. Best Buy CEO Corey Berry addressed tariffs last month, saying that price increases are likely.

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"While Best Buy only directly imports 2% to 3% of our overall assortment, we expect our vendors across our entire assortment to pass along some level of tariff costs to retailers, making price increases for American consumers highly likely," Berry told investors prior to President Trump's announcement.

Globally, from London to Tokyo, other stock markets also experienced setbacks on Thursday, indicating that it's not just American companies that are concerned about the impact of U.S. tariffs. The United States holds more than one-fourth of the world's economy.