It shows that when stock prices are rising, they rise quite a bit and for a long time. And when they fall, they fall only a little by comparison and for shorter periods.
Indeed, data from Dow Jones show that since 1900, the Dow Jones Industrial Average has experienced a drop of 5% or more 388 times — an average of once every three months. The data also show that drops of 5% or more tend to recover quickly. Declines of 10% or more recover within 10 months on average, and drops of 20% or more typically recover in just 15 months on average.
So if you see the stock market crashes, what you need to do? Nothing.
If you are investing for the long term, what the stock market does today, tomorrow, next week or next month doesn’t matter. With a long-term perspective, you can simply wait it out any market crash.