In the Crash of 1929, the Dow lost 48% of its value. Six months later it
rallied back 48% (because this was from a starting point half as high, this
meant it got back 52% of the loss from the Crash). In 2007–2009, the Dow lost
54% of its value. It has now rallied back 54%, or in other words, it has
regained 45% of this loss in value.

Japan has gone through a similar process of dealing with an exploded real-estate bubble. The Nikkei hit a peak of about 39,000 in 1989. It has moved downwards in a sawtooth pattern for the past 20 years, with big rallies in 95–96, 98–99, and 03–07. Today, 20 years after its peak, the Nikkei is at about 10,000.