Bank of Japan Gov. Haruhiko Kuroda's suggestion that further yen weakness is "unlikely" prompted the currency's biggest rally this year. Firms from Standard Chartered PLC to Bank of Tokyo-Mitsubishi UFJ Ltd. do not expect the gains to last.
The yen jumped 1.4 percent against the dollar on Wednesday after Kuroda's comments, accelerating a rebound from a 13-year low reached last week. The yen is the only major currency for which options show traders must pay a premium to protect against gains versus the greenback next month.
Strategists say this bullishness will prove short-lived as the BOJ keeps expanding the supply of yen into the economy to boost the nation's zero percent inflation rate. Kuroda is the most prominent official to enter the war of words waged in recent weeks against what the authorities see as volatile yen moves that may harm the economy.