Japan's suspected disposal of US Treasuries and other foreign securities to finance its unprecedented yen intervention has reignited market concerns over supply pressures in the American bond market.
According to foreign exchange reserve data released by Japan's Ministry of Finance on Monday, foreign securities holdings fell by $87.8 billion at the end of August compared with the previous month—a decline that closely mirrors the scale of intervention seen during that period. The ministry had previously confirmed that authorities deployed roughly ¥15.4 trillion (about $98.6 billion) for currency market action in the month through August 26, setting a new monthly record, with some operations conducted jointly with the United States. As a result, Japan's total foreign reserves dropped by $94.6 billion to $995 billion, breaching the trillion-dollar threshold.
The sheer size of this intervention, along with the potential knock-on effects its funding method could have on the Treasury market, has drawn intense scrutiny. Treasury Secretary Bessent recently announced that the government would double its long-dated bond repurchase program over the two months through November 4, a move widely read as an effort to cap upward pressure on long-end yields, underscoring Washington's growing sensitivity to bond market stability.
Foreign securities plunge signals clear Treasury selling
Ministry data shows foreign securities holdings fell by $87.8 billion at the end of August, nearly matching the month's intervention spending. Although the breakdown of these holdings—by composition or maturity—was not disclosed, market participants generally estimate that roughly 70% of Japan's reserves are invested in US Treasuries.
Price action offers further evidence: the 10-year Treasury note's price at the end of August was only slightly lower than at the end of July, suggesting valuation changes contributed minimally to the drop in foreign securities. That points firmly toward active selling by Japan rather than market-driven declines.
Record intervention with joint US-Japan coordination
Ministry figures reveal that in the month through August 26, Japanese authorities deployed approximately ¥15.4 trillion for currency intervention, the largest monthly figure on record, with a portion conducted in tandem with the US. This marks the biggest single-month yen action ever undertaken.
The intervention unfolded against a backdrop of significant pressure on the yen, forcing authorities to step in aggressively to shore up the domestic currency. The coordinated format also signals deeper policy alignment between Washington and Tokyo on exchange-rate matters.
As Japan again resorts to selling Treasuries to fund intervention, US officials—especially with midterm elections approaching—are paying heightened attention to bond market stability. Treasury Secretary Bessent's recent announcement to double long-term bond repurchase volumes through November 4 is widely interpreted as a deliberate push to keep long-end yields in check.
Tokyo's latest move shows that even with Washington increasingly jittery about Treasury market health, Japan remains willing to tap its US debt holdings when necessary.
Reserves below $1 trillion, yet room to maneuver persists
Although Japan's reserves have slipped under the trillion-dollar level to $995 billion, authorities maintain that the remaining buffer is ample to support future interventions. Beyond foreign securities, foreign currency deposits—another potential funding source—also fell by $6.9 billion at the end of August.
Notably, Finance Minister Satsuki Katayama indicated after the joint intervention that future actions could tap the Federal Reserve's Foreign and International Monetary Authorities (FIMA) Repo Facility. This tool allows Japan to secure up to $60 billion in daily liquidity without selling Treasuries, thereby limiting spillover to US bond yields and broadening the scope for further intervention.
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