The Japanese yen strengthened past 157 per US dollar and was the best-performing currency in the G10 group, gaining as much as 0.6% to touch 156.38 per dollar in Asian morning trading on September 30, 2026, after the Japanese government issued repeated warnings about the yen's weakness, with end-of-quarter capital flows also lending support. Atsushi Mimura, Japan's senior currency policy official, told Reuters that the prime minister and finance minister of Japan, as well as the United States, had sent very clear signals about the currency's weakness. Japanese Prime Minister Sanae Takaichi said US President Donald Trump expressed concern about the yen's weakness during their talks last week. Markets have increased bets that the Bank of Japan, or BOJ, may raise interest rates again as early as next month, after the BOJ lifted its policy rate to 1.25% earlier in September. The yen has now strengthened by about 3.6% since the start of this quarter, after the Japanese and US governments jointly intervened in foreign exchange markets in July to prop up the currency, marking the two countries' first joint intervention in 15 years.
BOJ rate-hike expectations plus Japanese/US official warnings and joint intervention drive yen strength against the dollar.
Rising BOJ rate-hike bets and yen strength push JGB yields up, so the 10Y yield rises (bond price falls).
