According to Fidelity, a bear market is when a stock market index falls by at least 20% from recent highs. A bull market marks a period of rising market index values. They signify an upward trend in stock prices. Bull markets tend to last longer than bear markets because stock prices tend to trend upward over time.

Trade tensions remain high despite President Trump's decision on Wednesday to temporarily freeze U.S. tariffs on dozens of countries.

US markets tumbled Thursday after the White House confirmed a 145% tariff rate on Chinese goods. The Dow plunged over 2,100 points intraday before recovering partially amid volatile trading.

The stock market crash of October 1929 signaled the end of the "Roaring Twenties" and the beginning of the Great Depression. This was the second day of the big drop, known as "Black Tuesday," which began one day earlier and occupies the next spot on this list. 3.) Oct. 28, 1929 (-38.33, -12.82%)

The S&P’s 9% loss since last Friday makes this stocks’ worst week since March 2020 and the fifth-worst week of the last 20 years, trailing only losses sustained in October 2008 and early 2020.

This week brought significant daily declines across major stock markets.The drops followed President Donald Trump's Wednesday announcement on tariffs, which include a 10% baseline tariff for all imports from all foreign countries,

Stocks fell sharply in early trading Monday, extending last week's massive sell-off, as the Trump administration showed no signs over the weekend of backing down from its plan to impose wide-ranging tariffs.