The following is an excerpt from a piece I originally wrote for Kiplinger’s.

The stock market is centuries old and steeped in lore. No one really knows where its vocabulary comes from. It’s thought that the expression “bear market” comes from the way a bear’s claws strike downward, just as the term “bull market” comes from the upward motion of a bull thrusting its horns.

But the truth is that the expressions have been around for so long no one really knows who thought them up or what exactly the origins were.

The current bear market is young, and we don’t yet know how long it will last or how deep the losses will be. Given its record speed thus far, it wouldn’t be surprising if the recovery were equally fast. But it’s also entirely possible that the psychological trauma will cause it to be much worse. At this stage, there’s no real way to know. But we can use history, and numbers, as a guide.

According to data compiled by Dow Jones, the median number of days between the S&P 500 hitting its peak and hitting its eventual low was 187 days. And the median time from entering a bear market to hitting its eventual low was 71 days. The median loss in each bear market was 32.9%.

Those are just medians, of course. Some bear markets are quicker, some drag out much longer. Some barely qualify as bear markets, falling just more than 20%, while others drop much farther. For example, the bear market triggered by the 2008 financial crisis saw the S&P 500 lose 51.9% of its value, and the 1973-74 bear market wasn’t far behind it, shedding 48.2%. But the bear markets of the 1950s and 1960s saw declines of just 21.6% and 22.5%, respectively.

At the rate things are moving, these words will be out of date by the time they are printed, but as I write, the current bear market has the S&P 500 down about 26%, or about 7 percentage points above the median decline.

There’s no good historical precedent here. The current coronavirus scare has been likened to the Spanish flu of 1918, though it’s hard to consider that a good comparison given that World War I was ramping up. But for what it is worth, the Dow Industrials only dropped about 11% during the worst of the flu scare.

Now, we’re ready to talk about what to expect, and how to invest in this bear market.

To finish reading, please see How to Invest in This Bear Market.