An interesting piece on BloombergView: "...since the end of World War II (1945), there have been 27 corrections of 10 percent or more, versus only 12 full-blown bear markets (20 percent or worse).” However, the data show that the distribution of corrections isn't smooth. Indeed, almost half (45 percent) of the corrections occurred either in the 1970s or the 2000s. Both eras were part of longer-term secular bear markets, characterized by strong rallies, vicious sell-offs and earnings contractions. It is noteworthy that almost half of the corrections occurred in two out of seven decades. I suspect this fact isn't a coincidence. From a 30,000 foot view, it may be a key to understanding how likely a more severe correction might be..."