NEW YORK —

A monthslong calm on Wall Street shattered Friday and U.S. stocks tumbled after President Donald Trump threatened to crank tariffs much higher on China.

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The S&P 500 sank 2.7% in its worst day since April. The Dow Jones Industrial Average dropped 878 points, or 1.9%, and the Nasdaq composite fell 3.6%.

Stocks had been heading for a slight gain in the morning until Trump took to his social media platform and said he was considering “a massive increase of tariffs” on Chinese imports. He is upset about the restrictions China has placed on exports of its rare earths, which are materials that are critical for the manufacturing of everything from consumer electronics to jet

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