US and Japan Unite Against Yen's Descent into Crisis

The US Treasury and Japan's Finance Ministry coordinated an unprecedented yen-buying intervention on July 31, marking their first joint action since 1998. The move was confirmed by both nations' finance ministers, who warned that they would not hesitate to intervene again if needed.

The intervention came after the yen (JPYUSD) plummeted to its weakest level in approximately 40 years, reaching nearly 164 per dollar on July 23. The combined efforts of the US and Japan drove the currency back to the 155-157 range by Monday morning.

The scale of the operation was extraordinary, with Tokyo selling as much as $59 billion in a single day, according to Bank of Japan data. On the US side, the Federal Reserve Bank of New York sold euros to purchase yen on behalf of the Treasury through Goldman Sachs (GS) and Morgan Stanley (MS).

The motivation behind the intervention was fundamentally one of self-preservation for the US. Japan holds $1.14 trillion in US Treasury securities, the largest foreign holdings of any nation. A collapsing yen would force Japan to sell those Treasuries, directly pushing up American borrowing costs at a time when U.S. debt has reached $39.84 trillion and annual interest payments already exceed $1 trillion.

Bessent emphasized that the Federal Reserve's FIMA Repo Facility was 'upsized' as part of the intervention, allowing Japan to obtain dollar liquidity without destabilizing US bond markets.