Stocks are on the cusp of a bear market. Here's how long they last and how bad they can get

The U.S. stock market moved closer to a bear market on Monday as investors continued to wallop equities as dismay over the expected economic impact of the coronavirus and a new oil fisticuffs between OPEC and Russia sent energy names spiraling.

A bear market is defined as a 20% decline in one of the major U.S. stock indexes, typically the S&P 500 or Dow Jones Industrial Average, from a recent 52-week high close. Both indexes on Friday closed firmly in "corrections," a term investors use to denote a market decline in a range between 10% and 19.99%.

Here's the historical round-up on bear markets, including how bad they get, on average, and typically how long they last.

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