The stock market is down more often than you might think. Beneath I repeat a simply analysis, made in R, of two ETFs on the Dow Jones Industrial Average and S&P 500 respectively. These indexes show how the stock market moved in a given year. Every red box in the graphs beneath depicts a year in which the trend was downward; green boxes depict years with an upward trend. The trend is determined with a simple linear regression.
Conclusion: these indexes have a downward trend in about 1 out of 3 years.
For those interested, the code is on Github.