Tokyo - Tokyo stocks dived on Monday morning as concern about the world economy and Britain's EU vote sparked a yen rally that hammered exporters including Toyota and factory robot maker Fanuc.
The benchmark Nikkei 225 index slumped 432.88 points, to 16 168.48 by the break, extending a global sell-off, while the broader Topix index of all first-section shares was down 35.31 points, at 1 295.41.
Markets are on edge as the US and Japanese central banks meet this week, with investors worrying about global growth and the possible impact of a British exit from the EU, as polls showed an exit is a real possibility.
Few expect any move on interest rates from the Federal Reserve this week, but observers are divided over whether the Bank of Japan (BoJ) will announce more stimulus after its policy meeting ends Thursday.
About 55% of economists in a Bloomberg survey think the BoJ will launch more easing measures.
The dollar sank to ¥106.19 from ¥106.93 on Friday in New York, hitting exporters' repatriated profits.
"Everyone's scared," Ryuta Otsuka, a strategist at Toyo Securities, told Bloomberg News.
"There are too many events coming up for investors to take a plunge."
In share trading Toyota dived 2.79% to ¥5 470, Nissan slumped 2.89% to ¥1 022.5 and Fanuc was 1.94% off at ¥16 405.
Weaker oil prices hit crude-linked shares. Energy explorer Inpex plunged 4.73% to ¥842.1 and refiner JX Holdings tanked 2.75% to ¥420.1.
Japan's benchmark 10-year bond yield fell to a record low of minus 0.165%, underscoring a flight to safety among jittery investors.