The Nikkei 225 measures the performance of 225 highly capitalised and liquid publicly owned companies in Japan from a wide array of industry sectors.

Subsequently, it lost nearly all these gains, reaching a post-bubble intraday low of 6,994.90 on 28 October 2008 — 82% below its peak nearly 19 years earlier.

On 15 March 2011, the second working day after the massive earthquake in the northeast part of Japan, the index dropped over 10% to finish at 8,605.15, a loss of 1,015 points.

The index continued to drop throughout 2011, bottoming out at 8,160.01 on 25 November, putting it at its lowest close since 31 March 2009.

[citation needed] There was concern that the rise since 2013 was artificial and due to purchases by the Bank of Japan ("BOJ").

[10][11] From a start in 2013, by end 2017, the BOJ owned circa 75%[12] of all Japanese Exchange Traded Funds ("ETFs"), and were a top 10 shareholder of 90% of the Nikkei 225 constituents.

[13][14] On 15 February 2021, the Nikkei average breached the 30,000 benchmark, its highest level in 30 years, due to the levels of monetary stimulus and asset purchase programs executed by the Bank of Japan to mitigate the financial effects of the COVID-19 pandemic.

As of July 2024[update], the company with the largest influence on the index is Fast Retailing (TYO: 9983), at about 10% weight.

As of October 2023, the Nikkei 225 consists of the following companies (Japanese securities identification code in parentheses):[24] Bold indicates the top ten by market capitalisation.