More than 100% of the Nikkei 225 index fell more than 1,000 points to 1,933.83 on Wednesday morning, the first day of the trading day.
In response, Japan’s benchmark Nikkeis benchmark rose nearly 1,300 points to 4,943.07.
The index closed below its 52-week high of 5,800.07 set last year.
The Nikkeys latest fall was its lowest since February 2008.
On Wednesday morning it closed at 1,952.83.
The Nikkeies closing was also its second lowest since October 2007.
The Nikko index, which tracks the index’s performance, fell 2.2% to 8,069.21, its second straight week of losses.
The Japanese central bank said it would cut rates for the first time in two years on Thursday.
“Our priority is to make sure the economy can withstand the shock of the crisis, and that our measures are adequate to ensure that we can carry out our macro-economic task,” Governor Akio Furukawa said in a statement.
Mr Furukaw said he expected the economy to expand at a 4.5% annual rate in the second quarter, down from a 5.2%-per-cent pace in the first quarter.
While the Nikko slumped 4.4%, the Nikkel fell 3.3%.
The Nikkel rose 2.6% to 6,853.83 in Tokyo.
Tokyo-listed shares of Japanese broadcaster NHK slid as much as 2.5%.
The yen strengthened against the dollar, and the euro also rose.
The S&P 500 index of the biggest US stocks closed up 0.9%.
The FTSE 100 index of world’s leading stock exchanges fell 0.2%.