Yen Gives Back Half Its Intervention Gains as USD/JPY Bears Eye Key Resistance Ahead of US CPI

The Japanese yen weakened roughly 1% on Monday, erasing half of the gains produced by a landmark coordinated intervention in which the US Treasury and Japan's Ministry of Finance jointly bought yen, their first such joint action since 1998 during the Asian financial crisis. The intervention, carried out late last week, lifted the yen from around 163 per dollar, a 40-year low, to approximately 155-157 per dollar. Japan is estimated to have deployed about 52.8 billion dollars in the operation, while the US Treasury, led by Secretary Scott Bessent, is believed to have committed between 5 billion and 10 billion dollars, a figure suggested by a notepad visible at a Camp David press event.

Both governments confirmed the effort Monday morning, citing a joint statement originally issued in September 2025 that called out excessive volatility and disorderly yen moves. As the initial boost fades, analysts and market watchers are questioning whether the intervention can hold. Questions centre on the limited firepower of the US relative to speculative selling pressure, and on whether the Bank of Japan will raise rates quickly enough to underpin the currency on fundamentals.

USD/JPY was approaching key technical resistance Monday, with traders wary of another round of coordinated buying. US CPI data due Wednesday is seen as the next major trigger, as a softer inflation print could ease dollar demand and reduce pressure on the yen, while a hot reading could embolden bears to test the resolve of both treasuries.