Yen traders are bracing for some sound and fury from the Japanese and U.S. central banks -- who each meet Sept. 20-21 -- even as they bet that the developed world’s best-performing currency will remain strong in the longer term. The premium for one-month options to buy the yen versus the dollar, over the cost of contracts to sell it, sank to 1.03 percentage points on Tuesday, the least bullish for the Japanese currency this month and down from 1.99 last week. Three-month risk reversals -- as the options gap is known -- were little changed at 1.94, blowing out the spread to the shorter-term contracts to the widest in six weeks.

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