The Nikkei 225 was the main Japanese stock-market benchmark during the 1990s collapse of Japan's asset bubble.
The index had surged during the late-1980s boom and reached a record intraday high of 38,957.44 on December 29, 1989. After the bubble burst, Japanese share and land prices declined, banks accumulated bad loans, and the economy entered a prolonged period of weak growth and financial stress. The Nikkei became the clearest public measure of the stock-market collapse.
The Nikkei 225 is a price-weighted index of 225 prominent companies listed on the Tokyo Stock Exchange's Prime Market. It is not the same as TOPIX, which is capitalization-weighted and covers a broader group of companies. That difference matters when comparing Japanese market performance. The index's prolonged fall is one reason Japan's post-bubble period is often called the Lost Decades.