Japan's Suspected $55 Billion Yen Defense Unsettles US Treasury Market

Japan likely sold its holdings of U.S. Treasuries to finance its largest-ever currency intervention, data suggests, creating a new headwind for the world's most important bond market. During the week ended May 6, a period when the Ministry of Finance is estimated to have spent about $54.7 billion buying yen, U.S. Treasuries held in custody at the Federal Reserve for foreign accounts fell by $8.7 billion, the first drop in a month.

"The change in custody holdings seems to coincide with the event of the Ministry of Finance instructing the Bank of Japan to intervene," Rodrigo Catril, a senior foreign-exchange strategist at Australia Bank in Sydney, said.

The decline in Treasury holdings points to a potential funding source for Tokyo's yen-buying operations. The move also coincided with a notable decoupling in the typical correlation between the dollar-yen exchange rate and the 10-year U.S. Treasury yield, which had tumbled as oil prices eased on hopes for a U.S.-Iran peace deal. While the S&P 500 and Nasdaq 100 rallied to record highs, the specter of sustained Treasury selling by a major holder introduced a new variable for investors.

The sales represent a significant shift for the Treasury market, which is already grappling with upward pressure on yields from higher energy prices and concerns over the U.S. fiscal deficit. While the initial amount is manageable, sustained intervention funded by Treasury sales could pose a "substantial problem" for a market that relies on foreign central banks as consistent buyers. The issue is expected to be a key topic of discussion when U.S. Treasury Secretary Bessent visits Tokyo for meetings with Prime Minister Tak市 Sanae and Bank of Japan Governor Kazuo Ueda.

Actual Sales May Dwarf Custody Data

The $8.7 billion reduction shown in the Fed's custody account may understate the true scale of the selling pressure. Strategists note that central banks often use their own cash reserves first, which don't appear in the Fed's data.

"Assuming the situation is the same this time, it means that the supply and demand in the relevant bond market—generally considered to be the U.S. Treasury market—will deteriorate by about $70 billion," Shusuke Yamada, a currency and interest-rate strategist at Bank of America in Tokyo, wrote in a research note. This larger figure aligns more closely with the estimated total intervention cost.

A New Headwind for Treasuries

The potential for sustained selling from Japan, the largest foreign holder of U.S. debt, comes at a precarious time. U.S. Treasury yields had already been climbing due to persistent inflation and the fiscal pressures of the ongoing Iran conflict. While yields recently dipped on signs of a potential de-escalation, the prospect of a major buyer turning into a seller complicates the outlook.

JPMorgan's Yuxuan Tang noted that Japanese authorities likely prefer to sell short-term Treasury bills to minimize market disruption, executing trades during liquid U.S. hours. However, if interventions become a regular occurrence, the cumulative effect could force yields higher, tightening financial conditions for U.S. corporations and consumers. This dynamic presents a new challenge for the Federal Reserve, with Governor Goolsbee recently noting that an AI-led boom without productivity gains could necessitate higher rates to prevent overheating.

This article is for informational purposes only and does not constitute investment advice.