U.S. markets tanked on Thursday, with the Dow Jones Industrial Average closing down 10 percent. The drop was the fourth-worst in history, and the worst since 1987's "Black Monday" market crash. The S&P 500 also had its worst day since 1987, closing down 9.5 percent. Both indexes have entered a bear market amid fears the global coronavirus outbreak could continue to affect the economy. A 7 percent drop Thursday morning triggered a "circuit breaker" to pause all trade at the New York Stock Exchange. Neither President Trump's efforts to promise a contained virus nor the Federal Reserve's moves to provide fiscal stimulus reassured investors. The other worst single-day drops in the market occurred in 1929 and 1931, amid the crash that caused the Great Depression.

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