雖然不能預知未來，但了解一點曆史也沒有壞處。道瓊斯指數自1946年以來有31次下跌10％，其中12次（約40％）開啟20％以上跌幅。

Since 1946, there have been 31 instances of a 10% drop. But a 10% drop doesn’t necessarily lead to a 20% one (which denotes a bear market) — in fact, in just 12 of those 31 instances did a bear market eventually ensue.