Thursday, the Japanese Nikkei 225 stock index crashed 6.4% (down a whopping 844 points to 12,445).
Nikkei futures have been rallying all day long, though – as U.S. stocks have advanced – and are currently trading at 13,080, up 635 points already from Thursday's close.
That implies a 5.1% surge when the Nikkei re-opens Friday in Japan.
Why is the Japanese stock market so volatile?
WSJ chalks it up to day trading, which has surged in popularity as the market has stage a wild advance this year as investors bet on the success of "Abenomics," an experimental stimulus program underway in Japan.
At 13,090, the Nikkei is 16.2% off its May 22 peak.
Nikkei futures rise during European and North American trading on Thursday, June 13.
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