Japanese Yen (JPY): More Than Intervention?

A Changing Policy Reaction Function

The Japanese yen has strengthened following coordinated action by Japanese authorities and the U.S. Treasury. That matters. Japan’s Ministry of Finance has been trying to stabilize yen depreciation for several years, with mixed and often temporary results. What is different this time is not simply that Japan is pushing back again. It is that the U.S. appears willing to be involved.

This should not be dismissed as another short-lived bout of intervention. Currency intervention rarely changes a trend by itself, but it can change market behaviour when it tells investors that the policy reaction function has shifted. 

Exhibit 1: USD/JPY and the changing policy reaction function

USDJPY

Source: Bloomberg Finance LP, Macrobond As of August 4, 2026

Exhibit 2: Further narrowing in rate differentials could support JPY

USDJPY vs. 10 year yield differential

Source: Macrobond Financial AB, Bloomberg, Macrobond As of August 4, 2026  

The signal here is that yen weakness may no longer be viewed only as a Japanese problem. It may also be viewed in Washington as part of a broader set of currency and trade imbalances that have left the U.S. dollar persistently strong and some trading partners with an advantage from weaker exchange rates.  

Fundamentals Are Becoming More Supportive

For much of the past decade, the yen has been the funding currency of choice. Extremely low Japanese interest rates, combined with higher yields elsewhere, encouraged investors to remain structurally underweight yen and overweight foreign assets. That trade has been powerful because it has had both a yield argument and a momentum argument. Investors were paid to be short yen, and for long stretches they were rewarded by the exchange rate as well.

That is why interest-rate differentials remain the key determinant of staying power. If Japanese rates remain far below those in the U.S. and other major markets, intervention can slow yen weakness but is unlikely to reverse it on a sustained basis. If those differentials continue to narrow, however, the yen could have more room to recover than markets currently assume.

There is also a valuation argument. On an inflation-adjusted purchasing power-parity basis, the yen remains deeply undervalued against the U.S. dollar.

Valuation is not a timing tool, and currencies can remain cheap for years when policy and yield differentials justify it. But the degree of undervaluation matters when the policy backdrop starts to change.

Canada is in a similar position, although less extreme, with the Canadian dollar also screening undervalued in our long-term capital market assumptions. The common thread is that persistent U.S. dollar strength has left several major currencies trading below long-term fair value estimates.  

Exhibit 3: The JPY is deeply undervalued

JPY Undervaluation Relative to USD

(CIGAM Long-Term Forecast*)

Source: Bloomberg Finance LP, Macrobond As of August 5, 2026 *2026 forecast used for entire time period

What Else Has Changed?

The shift in Japan is also domestic. Japanese government bond yields have risen from exceptionally low levels, and that changes the arithmetic for large Japanese institutional investors. For years, pension funds, insurers and other long-term allocators had strong incentives to invest abroad in search of yield. As domestic yields become more attractive relative to long-term liabilities, the case for allocating more capital back to Japan becomes more credible. Government efforts appear increasingly aligned with that objective: encourage domestic investors to bring more balance back to their portfolios and reduce the one-way pressure created by foreign asset accumulation.

This is where the yen story could get more interesting. If intervention, higher domestic yields and portfolio repatriation begin to reinforce one another, the market may no longer treat yen strength as a short-term squeeze. It could instead become the early stage of a broader reversal in one of the most crowded structural positions in global currency markets.

The broader implication is that this may not be only about Japan. It may be an early warning shot from U.S. officials that they are less willing to accept a global currency regime in which the U.S. carries the burden of a persistently strong dollar while other countries benefit from weaker currencies.

It is premature to call this a formal weak-dollar policy. But it is not premature to say the market should pay attention when the U.S. Treasury is willing to coordinate around yen strength after a long period of tolerance toward dollar strength.

That point matters for other currencies as well. A stronger euro or Canadian dollar would not necessarily face the same resistance from local policymakers that markets might assume. Stronger currencies can help reduce imported inflation and ease pressure on consumers.

The trade-off is that they can weigh on exporters, but the political economy has changed. After several years of inflation pressure, a firmer currency may be more acceptable than it would have been in a pre-inflation world.

The individuals involved also matter. Scott Bessent and Kevin Warsh both understand markets, the role of incentives and the way policy signals can move positioning without requiring unlimited balance-sheet commitment.

A coordinated, long-term framework between them could give this more durability than a one-off intervention headline. That does not make the outcome certain, but it raises the odds that investors should treat the recent move as strategically important rather than merely tactical.  

Investment Implications

For investors, the practical takeaway is not to assume a straight-line yen rally. The yen still needs help from fundamentals, especially narrower rate differentials and evidence that Japanese capital is beginning to rotate home. Energy prices also remain relevant, given Japan’s dependence on imported energy and the effect of oil prices on the trade balance. But the balance of risks has changed. The market is being asked to reconsider whether yen weakness remains a policy-tolerated trend or has become a policy-sensitive imbalance.  

Exhibit 4: Lower energy prices would support JPY

Japan's Goods Trade Balance

Source: Japanese Ministry of Finance (MOF), Macrobond As of July 21, 2026 *GFC: Global Financial Crisis  

A stronger yen should also not be viewed automatically as negative for Japanese equities. Exporters may face a headwind if currency strength is abrupt, but a more stable currency can improve domestic purchasing power, reduce imported-cost pressure and support confidence in Japan’s economic normalization.

The more important question is whether yen strength is accompanied by higher domestic yields, better capital allocation and continued corporate governance reform. If so, the investment case for Japan can remain intact even with a firmer currency.  

Bottom Line

The bottom line is that this may be more than intervention, even if it does not amount to a U.S. weak-dollar policy. Japan has been trying to stabilize the yen for years. The change is U.S. Treasury involvement, which puts yen weakness into a broader debate about currency values, trade advantages and the burden of a persistently strong dollar. Bessent’s point that dollar strength is not simply the level shown on a Bloomberg screen is important.

The dollar’s reserve-currency role rests on stability, policy credibility and deep liquidity, not its value on any single day. That distinction matters. It is too early to call this a secular weak-dollar shift, but policy coordination, extreme yen undervaluation, narrower rate differentials and the potential for Japanese capital to rotate home make this a signal worth taking seriously.  

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GLOSSARY:

Bond yield: The interest earned on a fixed-income security.

Liquidity: The degree to which an asset or security can be quickly bought or sold in the market without affecting the asset’s price. Cash is considered to be the most liquid asset, while things like fine art or rare books would be relatively illiquid.