The Japanese yen weakened to approximately 159 per U.S. dollar. This decline erases nearly half the gains following a coordinated intervention by Japanese and U.S. authorities in late July and early August.
The joint action represented the first such effort since 1998. It originally moved the yen from a near 40-year low of approximately 164 per dollar.
Persistent interest rate differentials between the Bank of Japan and the U.S. drive the currency's slide. Investors continue to use carry trades to borrow yen and fund higher-yielding assets elsewhere.
Traders are now monitoring authorities for potential further action as the previous intervention's impact fades.