Compared to the period from 1950 through 1980, the S&P 500 (Index: SPX) of the last four decades experiences notably fewer long losing streaks. But during the last twenty years, those losing streaks have become substantially deeper.
We've calculated the smallest, largest, median and mean declines the S&P 500 experience during its longest losing streaks of six trading days or longer in duration beginning in the periods of 1950 through 1980, 1981 through 2000, and 2001 through this point of 2021. That information is visualized in the following chart:
The median and mean decline of the index' value is roughly similar in the periods for 1950-1980 and 1981-2000, although the number of losing streaks declined. But since 2000, while the number of long losing streaks has continued to fall, the magnitude of the associated decline of stock prices has become much larger when they have occurred.