But economic and fiscal policy minister Heizo Takenaka said the decline was not too rapid, leaving foreign exchange traders flummoxed as to whether or not the Japanese government will act to strengthen the yen.
The Bank of Japan decided against buying ¥200 billion of foreign bonds at a policy meeting in November, after considering a motion put forward by board member Nobuyuki Nakahara. The board member denied it would constitute a form of currency intervention.
But some dealers believe the yen still has more ground to lose against the dollar, despite the apparent ambiguity on Japanese monetary policy. Proprietary traders at a major US investment bank were said to have bought short-dated, one-month yen puts/dollar calls on a total notional of at least $2 billion, according to one recent press report. Such a position is a one-way bet that there will be further declines in the yen's value against the dollar.