Japan's prolonged asset-price collapse that began after its 1989 market peak is commonly called the Lost Decade.
The phrase originally described the 1990s, when Japan struggled with weak growth, falling asset prices, banking problems, and deflation. The Nikkei 225 reached its record closing level of 38,915.87 on 29 December 1989. It then plunged as the country's property and stock-market bubble burst.
Japanese banks were left with large volumes of bad loans, and the financial system took years to recognize and resolve the losses. Businesses reduced investment, households became cautious, and repeated stimulus measures did not quickly restore strong expansion. Because stagnation continued into the 2000s, some economists use “Lost Decades” in the plural.
The episode was not a single trading-day crash. It was a long adjustment after an extraordinary credit and property boom. Japan's experience later became a reference point in discussions about asset bubbles, deflation, and the danger of delaying bank restructuring.