Share prices tumbled Friday on the Tokyo Stock Exchange, with the benchmark Nikkei Average plunging below the 15,000 mark for the first time in about 16 months.
The Nikkei ended the morning session at 14,874, down 838 points or 5.34 percent from Wednesday's close, public broadcaster NHK reported.
The market was closed on Thursday.
The sell-off on the bourse was on the back of the yen's sharp appreciation against the dollar, fuelled by concerns over the global economic outlook.
Market sources said crude oil futures are also plunging, increasing risk-aversion among investors.