Yen Carry Unwind Risk Returns as US Joins Tokyo Intervention

Coordinated intervention returns

The Federal Reserve Bank of New York sold euros for yen through Goldman Sachs and Morgan Stanley on 31 Jul on behalf of the US Treasury, according to the Financial Times. 

USD/JPY had broken above ¥163 on 21 Jul, a level unseen since 1986. Japan's Ministry of Finance responded on 30 Jul with an estimated ¥8.45tn (roughly $52.8bn at intervention-day spot near ¥160) of yen buying in a single session, based on BoJ account data and broker estimates. That approached the ¥11.7tn Tokyo spent across the entire April-May 2026 round, itself a monthly record. The pair closed at ¥157.40 by Friday's New York close.

Finance Minister Satsuki Katayama confirmed the US-Japan coordinated action in a statement on 3 Aug, saying Tokyo "will not hesitate to conduct further joint intervention." US President Donald Trump told reporters on 3 Aug that Japan "wanted a little bit of help" and that Washington was "always there" for the ally, citing what he described as a good relationship between the two countries.

US Treasury Secretary Scott Bessent, photographed at Camp David with a notepad reading "To Do" followed by "Buy Japanese Yen (JPY) $5-10 bil" (implying a $5bn to $10bn purchase), said in a post on X late on 2 Aug that Friday's actions "countered disorderly yen movements" and that the US "will not hesitate to participate in further joint intervention."

Echoes of 2024 unwind

Digital assets, trading around the clock and carrying heavy leveraged positioning, tend to react first and most sharply when yen funding costs rise abruptly. 

The reference point is the first week of August 2024, when a surprise Bank of Japan (BoJ) rate rise combined with weak US jobs data forced a violent unwind. Bitcoin opened August 2024 near $64,600 and traded as low as $49,000 on 5 Aug. Ether, which opened the month near $3,200, fell to $2,100 over the same window, according to TradingView data. The Nikkei 225 lost 12% in a single session.

Jonas Goltermann, chief markets economist at Capital Economics, told Reuters a repeat episode was possible this time, though smaller in scale. Gross yen shorts have been trimmed since 2024, but leveraged positioning rebuilt over the past year as USD/JPY drifted higher. 

So far the crypto market has absorbed the intervention without material damage: BTC was trading at $63,144 as of 02:00UTC on 3 Aug, roughly 1.3% below its 30 Jul level of $63,963, according to TradingView data.

Washington's stake

For the US Treasury, an undervalued yen carries its own costs: it widens the US-Japan trade deficit and complicates the administration's manufacturing rebalancing push. 

In the X post, Bessent framed the operation in alliance terms, saying "economic security is national security" and that "the US-Japan alliance is built on both." He said Friday's actions "countered disorderly yen movements" and that the US "will not hesitate to participate in further joint intervention." He also said the Takaichi government is moving into "an exciting new phase of Abenomics," the aggressive easing and stimulus programme launched by former prime minister Shinzo Abe in 2012 to end decades of deflation.

Trump said he expected Washington to gain financially from the intervention.

A different trigger

What differs now is the trigger. In 2024, the shock came from the BoJ. This time the strengthening has been engineered by two treasuries acting in concert, with Bessent framing the yen as suffering from "substantial undervaluation" that Washington is prepared to help correct. Derivatives markets now price a 40% chance of a 25 basis-point BoJ hike in September, up from 30% a week earlier, according to the Financial Times.

Bessent also called for the Fed's Foreign and International Monetary Authorities (FIMA) Repo Facility to be "upsized in the coming months," a step that would give allied central banks greater access to dollar funding without selling their US Treasury holdings.

Traders are already probing the ceiling. One Asian bank told the Financial Times that clients were putting on fresh yen shorts targeting ¥162. Whether the crypto complex escapes a bumpier ride depends on whether that resistance holds through the G20 finance ministers' meeting in Asheville, North Carolina, on 31 Aug – 1 Sep, where Bessent and BoJ Governor Kazuo Ueda are due to meet.