Anatomy of a Currency Intervention: How the U.S. and Japan Defend the Yen

The United States and Japan conducted a coordinated intervention on July 31 to support the struggling Japanese yen, an action designed to increase demand for the currency and signal a united policy front. According to analysis from BofA Global Research, the immediate goal was to push the U.S. dollar below the 155 yen level, a key psychological threshold.

How Intervention is Funded

Coordinated interventions amplify the financial firepower of any single nation. Japan's Ministry of Finance typically funds these operations by drawing from its massive $1.3 trillion foreign-exchange reserve portfolio.

As of the end of June, these reserves included:

• $162 billion in deposits
• $929 billion in securities, a significant portion of which is believed to be U.S. Treasuries

While Japan can generate approximately $27 billion in monthly liquidity from maturing assets and interest without outright sales, recent interventions may have surpassed ¥10 trillion over just three trading days. An operation of this magnitude would likely force the ministry to sell securities or use alternative funding mechanisms.

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The Role of Central Banks and Special Facilities

To avoid disrupting the U.S. bond market with large sales, Japan can utilize the Federal Reserve's FIMA (Foreign and International Monetary Authorities) repo facility. This allows foreign central banks to temporarily exchange their U.S. Treasury holdings for dollars. However, Japan's access is currently capped at a $60 billion counterparty limit, and its relatively high cost could restrict its use, according to the BofA report.

The U.S. Treasury funds its side of the intervention through its Exchange Stabilization Fund. For the July 31 operation, Washington reportedly sold euros to purchase yen, rather than selling U.S. dollars directly. The Federal Reserve can also participate in these operations, though it is not obligated to do so.

Market Impact and Outlook

The coordinated action demonstrates a powerful commitment that extends beyond Japan's own reserves, signaling to markets that further policy moves, such as faster Bank of Japan rate hikes or fiscal adjustments, could follow. In response to the intervention, BofA Global Research analysts lowered their year-end USD/JPY forecast to 149 from a previous estimate of 152, anticipating a stronger yen.