The 1930s And 1970s
For those who take a bearish view, the 1930s are a potential omen. Though most declines and falls in recent history have taken longer on the way down and longer on the way up, the 1930s paints quite a different picture for the markets. The entire decade is almost filled with violent swings in the stock market. Yes the decade as a whole was certainly a losing one for investors so the downswings dominate for the buy and hold investor, but that conceals eight distinct and powerful stock-market rallies during the decade. The 1930s were marked by volatility throughout, unlike in more recent history where any more extreme downward moves have been followed, sooner or later, by a rally. This is why those who are bearish use the 1930s as an analogy. It shows how the current rally may not be sustained.
The inflationary period of the 1970s and early 1980s too provide some ammunition for bears. Here too there were violent swings in the markets, and though the overall direction was not quite as bearish, markets did tread water for much of the decade. Many apparent recoveries from market lows were then met with subsequent declines. Many rallies did not hold during the 1970s just as in the 1930s.