Japan Sold $87.8 Billion of Foreign Securities to Pay for Its Largest Monthly Yen Intervention

Japan's holdings of foreign securities fell by $87.8 billion at the end of August compared with a month earlier, The Japan Times reported, a decline close to the scale of the intervention Tokyo ran to support the yen. Japanese authorities spent about 15.4 trillion yen ($98.6 billion) in the month through 26 August, the largest monthly total on record according to Bloomberg, and part of the operation was conducted jointly with the United States.

The arithmetic points to one conclusion. A government that needs a large amount of dollars quickly sells the dollar assets it already holds. Japan's finance minister has since said future dollar-selling operations will be funded through the Federal Reserve's repurchase facility for foreign and international monetary authorities, which lends dollars against Treasury collateral instead of forcing an outright sale. That change is an admission that the first method carried a cost in the bond market.

The timing matters because longer-dated United States Treasury yields are already under pressure. The ten-year Treasury yield stood at about 4.78% on 4 September, and a majority of participants in a Bloomberg survey expect thirty-year yields to finish the year at or above 5%. The Financial Times argues that yields have simply returned to something like a normal range after two decades of suppression, and separately that a decisive move through 5% would raise the cost of capital enough to slow the artificial-intelligence investment boom that has driven gains in equity indices.

The episode shows what happens when two central banks pursue different policies and neither wants the resulting exchange rate. Intervention addresses the exchange rate directly, but the rate keeps moving because the interest-rate gap that caused it has not closed. The cost falls on the intervening government's balance sheet and reduces the pool of price-insensitive buyers for American debt.