Japan and the United States have confirmed they jointly intervened in currency markets last week to arrest a slide in the yen, which had fallen to a fresh 40-year low. It is the first joint intervention by the two countries since 2011, when they coordinated action after the earthquake and tsunami in eastern Japan, and both governments say they are prepared to intervene again to prevent volatility in the yen and Japanese government bonds from destabilising the global economy, including pushing up US borrowing costs.

Bank of Japan data suggest Tokyo sold close to $59bn to buy yen during an initial move on Thursday, before Friday's confirmed joint action with Washington, while the US has not disclosed its own figure, though a photographed notepad belonging to Treasury Secretary Scott Bessent referenced buying $5-10bn of yen. The yen's weakness largely stems from the gap between Japan's interest rates, raised to 1% in June, and the US Federal Reserve's rate of 3.50%-3.75%, compounded by Japan's shrinking workforce and reliance on dollar-priced energy imports. Following the intervention and comments from President Trump and Bessent backing Japan's efforts, the dollar eased from last month's 40-year high of 164 yen to trade around 157-158 yen.