The Nikkei 225 lost more than 80% from its 1989 peak to its 2008 low.
The index reached an all-time closing high of 38,915.87 on 29 December 1989, at the height of Japan’s asset-price bubble. After the bubble burst, Japanese share prices declined for years. The Nikkei 225 eventually reached a closing low of 7,054.98 on 28 October 2008 during the global financial crisis.
The collapse was connected to excessive lending, soaring land and share prices, and later attempts by authorities to contain inflation and financial excess. Japan then experienced a long period of weak growth, banking problems, and deflation, often called the Lost Decades.
The Nikkei 225 is Japan’s best-known stock index, but TOPIX is another important Japanese benchmark. The question refers specifically to the Nikkei’s peak-to-2008-low decline, not to a permanent loss or to the performance of every Japanese share.