Yen intervention: what history tells us about last week's dramatic USD/JPY reversal

Yen intervention: what history tells us about last week's dramatic USD/JPY reversal

The Japanese yen staged one of its sharpest rallies in years last week, after Japan and the US confirmed coordinated intervention in the foreign exchange market to halt the currency's slide. The move pushed USD/JPY sharply lower from the 164 area towards 155, in a dramatic reminder that even one of the world's deepest currency markets can be disrupted when policymakers decide that exchange-rate volatility has gone too far.

Japan's Ministry of Finance confirmed that Tokyo had intervened alongside Washington, while Bank of Japan money-market data suggested that Japanese authorities may have spent as much as $36.6 billion buying yen on the final trading day of July. Estimates of the broader operation have subsequently been considerably higher, with some analysts putting Japan's intervention at around $75 billion, although the precise amount remains uncertain.

The intervention came after USD/JPY reached around 164 yen, taking the yen to a 40-year low. Within days, the pair had fallen towards 155, representing a move of almost 9 yen, or more than 5%, from the peak.

USD/JPY weekly candlestick chart

The speed of the reversal was characteristic of an intervention-driven market: once traders recognise that a central bank or finance ministry is willing to step in aggressively, speculative positions can unwind very quickly.

Importantly, however, it is technically the Japanese Ministry of Finance, rather than the Bank of Japan itself, that decides when to intervene. The BOJ executes the transactions on the ministry's behalf. That distinction matters because the latest operation was not simply a monetary-policy decision by Japan's central bank; it was a government attempt to influence the exchange rate.

For those trading forex, understanding the mechanics and history of currency intervention is essential context for navigating periods of sharp and sudden volatility in pairs like USD/JPY.

A return to the intervention playbook

Japan has a long history of entering the currency market, although the motivation has changed substantially over the past three decades.

In the late 1990s, the yen was under severe pressure following the Asian financial crisis. In June 1998, Japan and the US conducted a surprise coordinated intervention after the yen had fallen to an eight-year low. The yen appreciated by more than six yen against the dollar in the immediate aftermath.

USD/JPY quarterly candlestick chart

The episode is particularly relevant today because last week's operation was the first joint US-Japanese yen-buying intervention since 1998. The symbolism is therefore considerable: Washington has historically been reluctant to intervene to strengthen the yen, making the decision to participate in 2026 a significant escalation.

The direction of intervention subsequently changed. Between 2003 and early 2004, Japan was attempting to weaken the yen rather than strengthen it. Authorities conducted a huge campaign of dollar buying and yen selling, spending around ¥35 trillion. The objective was to prevent excessive yen appreciation and protect Japan's exporters.

That period demonstrates an important feature of Japanese intervention: policymakers do not necessarily target a specific exchange-rate level. Instead, intervention tends to be directed at what authorities regard as excessive or disorderly moves.

The next major phase came in 2010 and 2011. With the global economy still dealing with the aftermath of the financial crisis, the yen became a safe-haven currency and appreciated sharply. Japan intervened in September 2010, its first intervention in six years, after USD/JPY fell to around 82.87.

Following the devastating March 2011 earthquake and tsunami, Japan again became involved in coordinated intervention with other major economies as the yen surged amid repatriation flows and safe-haven demand.

The pattern then changed dramatically. For more than a decade, Japan largely stayed out of the market. That restraint ended in 2022.

2022: the return of yen-buying intervention

In September 2022, Japan intervened to support the yen for the first time since 1998, after USD/JPY broke through the 145 level. Further operations followed in October, with Japan ultimately spending ¥6.35 trillion, or roughly $42.8 billion at the time, on intervention during October 21-24 alone.

The fundamental problem was familiar: an enormous interest-rate differential. The Federal Reserve was aggressively raising rates while the BOJ maintained an ultra-loose monetary-policy stance. Traders borrowed yen and bought higher-yielding currencies, helping to drive USD/JPY higher.

The same structural problem returned in 2024. Japanese authorities intervened in April-May and again in July as USD/JPY approached and then exceeded 160. On July 11 and 12, 2024, the Ministry of Finance spent ¥5.53 trillion, or roughly $36.8 billion, buying yen and selling dollars. USD/JPY subsequently fell from 161.76 to around 157.30.

The parallels with 2026 are striking.

Can intervention really change the trend?

History suggests that intervention can be extremely effective in the short term but is much less powerful against a persistent fundamental trend.

The immediate impact is normally substantial. Authorities have enormous financial firepower, while intervention can trigger stop-loss orders and force leveraged investors to unwind carry trades. This can turn a gradual currency move into a violent reversal.

The longer-term impact is more complicated.

If the interest-rate differential continues to favour the dollar, investors may eventually return to selling yen. That is precisely what happened after several previous interventions. The yen's recent recovery has already started to lose momentum: by August 11, USD/JPY was back near 159, despite the scale of last week's intervention.

That raises the central question for markets: was last week's intervention the beginning of a sustained change in the yen's trend, or simply another opportunity for policymakers to slow the market down?

The role of monetary policy in determining what comes next

The answer may depend less on the size of the intervention than on monetary policy.

If the BOJ raises rates or signals a significantly more hawkish path while the Federal Reserve becomes less supportive of the dollar, intervention could act as a catalyst for a much larger yen recovery. If, however, US-Japanese interest-rate differentials remain wide, intervention alone may struggle to keep USD/JPY lower.

There is another important difference this time. The US is involved. Washington's participation gives the operation considerably more political and financial weight than Japan acting alone. US Treasury Secretary Scott Bessent has said Washington is prepared to do "whatever it takes" to support Japan in stabilising the yen, while the Federal Reserve's FIMA facility provides an additional potential source of dollar liquidity for the operation.

For currency traders, the lesson from the past is therefore clear. Intervention can change market psychology almost instantly, but it rarely changes economic fundamentals by itself.

Understanding how to trade forex around high-impact events like central bank intervention is an important skill. Our forex trading platform gives you access to USD/JPY and a wide range of other major and minor currency pairs, with the tools to act quickly when market conditions shift.

What the history of intervention means for traders now

Last week's collapse in USD/JPY from 164 towards 155 demonstrated the power of coordinated intervention. Whether it ultimately marks the beginning of a structural yen recovery, however, will depend on what happens next with Japanese and US interest rates.

For now, the message from Tokyo and Washington is unmistakable: 160-165 USD/JPY is no longer simply a market level. It has become a policy battleground.

This doesn’t exclude another run at that resistance area taking shape in the coming weeks. After all the sharp decline in late January and swift sell-off in late April were both followed by another up leg taking the USD/JPY cross to new 2026 highs.

USD/JPY daily candlestick chart and Fibonacci retracement levels

Since last week’s ¥155.23 near 3-month low – made close to the ¥155.03 early May trough – the cross has already risen towards the halfway point - or 50% retracement - of its July-to-August decline around ¥159.62.

Last week USD/JPY stalled on Thursday and Friday around the 38.2% Fibonacci retracement at ¥158.58 – which should now act as support, together with the 200-day simple moving average (SMA) at ¥158.10 - before breaking through it on Monday.

A rise above the 50% retracement at ¥159.62 would likely unleash a move towards the 61.8% Fibonacci retracement at ¥160.66. From there it probably won’t be that difficult for the currency pair to advance towards the 78.6% Fibonacci retracement at ¥162.33.

Technically speaking USD/JPY will be deemed to be in a long-term uptrend while the May-to-August lows at ¥155.23-to-¥155.03 underpin on a weekly chart closing basis.

Those looking to trade the yen can do so through spread betting or CFD trading, both of which offer access to forex markets including USD/JPY, with the ability to go long or short depending on your view of where the pair is heading next.

How to trade USD/JPY

1. Do your research on USD/JPY, the interest rate differential between Japan and the US, and the latest intervention developments
2. Decide whether you want to trade via spread betting or CFD trading
3. Open a forex trading account with us
4. Search for USD/JPY in our trading platform
5. Place your trade