A more than five per cent plunge in Tokyo led another Asian rout Friday, bringing to an end one of the most painful weeks for investors as fears about the global economy - and possible recession - stalk trading floors.
The steep losses in Japan came as the yen pushed to more than 16-month highs against the dollar and dealers continued a flight to safe havens.
However, oil soared almost six per cent following a report that producers' group OPEC could be willing to co-operate on output cuts to stem a crash in prices that has sent shockwaves through world markets.
The losses across equities are the latest of a sell off that has wiped trillions off valuations from Asia to the Americas this year.
And analysts say there is growing concern that central banks are running out of ideas to provide support, with Sweden's saying it would push its interest rate further into negative territory, weeks after Japan adopted the policy for the first time.
The measure - effectively charging lenders to park cash with it - follows similar moves by the European Central bank and Switzerland.
And while Federal Reserve boss Janet Yellen told congress Thursday it was unlikely the US would also need to adopt such extreme measures, she did leave open the possibility.
"Central bank policies and the uncertainty around their effectiveness is the big macro concern right now," Leo Grohowski, chief investment officer of BNY Mellon Wealth Management in New York, told Bloomberg News.
"There's a large disconnect right now between what the Fed might do and what they're saying and what the market is expecting. There's a lot of Fed uncertainty back on the table." Concerns that the upheaval that has wracked world markets will now seep into the US economy, the world's biggest, is adding to selling and financial stocks - particularly banks - are coming under intense pressure.
Tokyo stocks plunged 5.3 per cent by the break. The Nikkei index has lost 10 per cent this week, despite being closed on Thursday for a holiday.
Hong Kong fell one per cent after a near four per cent fall Thursday, Sydney shed 0.9 per cent, Seoul was 1.4 per cent lower and Wellington eased more than one per cent.
The selling followed huge losses on Wall Street and in Europe.
Juichi Wako, a senior strategist at Nomura Holdings in Tokyo, said: "We're not simply in a risk-off mode, the market's fallen to the point of pricing in a recession in the US. The market is saying we're worried no matter what Yellen says." With investors pulling out of high-yielding - riskier - assets, safe havens such as the yen are benefiting.
The Japanese unit soared more than seven per cent against the dollar this year and on Friday hit its highest level since the end of October 2014.
The greenback touched 112.10 yen in early trade, from 112.39 yen late Thursday in New York, and far below the 114.67 yen it was trading at on Wednesday in Tokyo before the holiday.
However, on oil markets West Texas Intermediate soared 5.4 per cent and Brent added 5.1 per cent after a Wall Street Journal report in which the United Arab Emirates' energy minister said "everyone (in OPEC) is ready to co-operate" on an output cut.
While there is much scepticism that any progress to slash production will be made, the news provided some respite to a market that has seen prices plummet about 20 per cent this year alone.