Yen intervention: what the US-Japan rescue means for JPY, USD and EUR

What happened: Japan's record yen intervention and Washington's backing

Japan spent an estimated ¥8.45 trillion (roughly $53 billion) defending the yen on 30 July, its largest single-day intervention on record, after USD/JPY slid to 40-year lows. Tokyo followed with the first joint intervention alongside the US since 2011, committing a further $36 billion on 31 July. Washington's contribution remains unconfirmed, though a handwritten note photographed on Treasury Secretary Bessent's notepad put the estimate at $5 – 10 billion. The scale of the action signals genuine determination to stabilise the currency.

Washington had its own reasons to act. Japan held $1.091 trillion in foreign currency reserves at end-June, according to Ministry of Finance data, with analysts estimating roughly 70% held in US Treasuries. Set against $31.68 trillion in Treasuries held by the public, that represents a meaningful slice of the market. Large-scale sales to fund yen-buying risk pushing yields higher still, with the 10-year already at 4.75% and the 30-year at 5.28% ahead of the intervention. Acting jointly, and drawing on the Federal Reserve's (Fed) Foreign and International Monetary Authorities (FIMA) repo facility, allows Tokyo to defend the yen without dumping Treasuries into an already-strained market.

USD/JPY outlook: can the intervention hold?

We doubt this reverses the underlying trend; it is a bandage rather than a cure — sufficient to discourage speculative shorts for now, but not to fix the structural imbalance. The bigger question is timing on the Bank of Japan's (BoJ) next hike: policymakers upgraded their growth and inflation outlook, but markets stopped short of reading that as a clear signal, even as the intervention lifted the odds of a September hike to 44%, from around 30%, according to LSEG data. A gradual repatriation of Japanese capital, including a possible shift by the Government Pension Investment Fund (GPIF), offers further structural support.

Officials have left the door open to intervening again. Bessent has said Washington 'will not hesitate to act', while Tokyo's Atsushi Mimura noted in May that the International Monetary Fund's (IMF) free-floating classification does not cap intervention frequency — though more than three interventions in six months could call that status into question. We believe Japan will avoid testing that threshold except in genuinely disorderly conditions, since reclassification would undercut the very credibility the intervention is meant to protect.

Absent further action, 155 has held as the floor so far, with USD/JPY already rebounding to above 157. The April–May intervention took roughly six weeks to fade, and a similar drift back towards the levels seen before the July intervention would not surprise us.

Technically, the pair is testing its 200-day moving average (MA); reclaiming the level would open the way towards 162 – 163, the 50% Fibonacci pitchfork level, while 155 should offer firm support on any renewed pullback.

USD/JPY daily price chart

Dollar index: firmer than initially expected

The dollar has proved more resilient than Wall Street expected at the start of the year, as the Middle East war stoked safe-haven demand and inflation risk, prompting the Fed to keep a 2026 hike on the table rather than the two-to-three cuts priced in during January.

The dollar index (DXY) fell to a seven-week low of 99.42 on 3 August following the intervention, down 1.0% over the week. We expect the index to hold broadly between 99 and 101 over the medium term, with Middle East risk supporting safe-haven demand and a possible hike still in play, particularly should the conflict re-escalate or tariffs resurface.

Technically, the DXY is shifting from corrective Elliott Wave A into Wave B, with the rebound potentially reaching the 50-day MA near 100.5 before turning lower. The 200-day MA will be watched closely as a critical support level.

US dollar index daily price chart

Euro outlook: EUR/USD caught in the intervention crossfire

EUR/USD fell immediately after the intervention, as the New York Fed sold euros to help fund the yen purchases, and has since stabilised near 1.15. Fundamentally, a second-quarter (Q2) gross domestic product (GDP) flash of 0.4% quarter-on-quarter beat expectations, and war-driven inflation risk should keep the European Central Bank's (ECB) tightening bias intact — both euro-supportive.

The intervention, however, introduces a new risk: a shift in where carry trades are funded. Borrowing cheaply in yen to fund higher-yielding dollar assets has long been a popular strategy; with authorities now determined to support the weak yen, capital may rotate towards other low-yield funding currencies, including the Swiss franc and the euro. Recent data reconciles with this trend: speculative net short EUR positions, per LSEG-compiled Commodity Futures Trading Commission (CFTC) figures, rose to $10.3 billion as of 28 July, the highest since February 2020.

CFTC speculative traders' net USD/EUR positions ($ billion) versus USD/EUR

The figures stated in this article are based on a snapshot taken on 5 August 2026 unless otherwise stated. Past performance is not indicative of future results.