Japanese Finance Minister Satsuki Katayama will announce on Monday that Japan and the US took joint action to arrest the yen’s slide to 40-year lows, two sources told Reuters. The operation, the first since 2011, seeks to boost the currency from its weakest levels since 1986. Katayama is expected to stress both nations' determination to combat excessive yen declines.

The Ministry of Finance and US Treasury have reportedly engaged in yen-buying interventions, with the Bank of Japan maintaining policy while signaling potential rate hikes. Treasury Secretary Scott Bessent, who recently stated the yen is "very undervalued," was seen with a note detailing plans to buy JPY (US)$5 bil-(US$)10 bil. The US Treasury has also alerted banks to prepare for possible intervention.

Officials declined to comment further due to the matter's sensitivity.