Japan and South Korea Intervene in Forex

Japan and South Korea have taken unusually forceful steps in foreign exchange markets this year, selling US dollars at key moments to defend their currencies.

Both Tokyo and Seoul are using dollar sales to mitigate sharp currency depreciation, driven by the need to stabilize domestic purchasing power. Analysts emphasize that these moves are tactical currency management rather than a permanent exit from the dollar.

Japan, a major importer of energy, food, and raw materials, faces higher costs for these goods due to a weaker yen.

While a weak yen boosts export earnings, rising global energy prices exacerbate the inflationary impact of a depreciating currency. Japanese authorities sold dollars to buy yen, aiming to curb excessive volatility.

Between April and June, 11.7349 trillion yen was spent, followed by an additional 15.3993 trillion yen from July 30th to August 26th. The July intervention was coordinated with the US Treasury, underscoring international cooperation.

South Korean authorities intervened on July 30th to support the won, leading to speculation about coordinated responses with Tokyo and Washington.

Deputy Finance Minister Munji Sang confirmed close trilateral communication, highlighting regional coordination among Asian financial authorities to manage currency pressures.

Historically, Japanese pension funds and insurers invested heavily in US assets for higher returns.

Improving returns on Japanese domestic bonds are now causing institutions to reconsider overseas exposure, and a reduction in Japanese demand for foreign government bonds could impact US financial markets long-term.

Japan's US Treasury holdings dropped to $1.104 trillion by the end of July 2026, a decrease from $1.1117 trillion in June.

The US Treasury cautions that reported data may not strictly equate to direct government selling due to third-country custodians, but it suggests a trend of Japanese capital looking inward, which has implications for US budget deficits and debt refinancing.

On October 1st, 2026, the 10-year US Treasury yield reached 5.34%, marking its highest level since 2002.

Rising yields can increase mortgage rates, raise borrowing costs for companies, and affect credit card and consumer financing, while also impacting the relative attractiveness of stocks and other investments.

Despite some investors reducing Treasury exposure, US Treasury data for July showed a net foreign capital inflow of $83.7 billion.

Official institutions purchased $44.4 billion in long-term securities, and Treasury bill holdings grew by $38.8 billion, demonstrating that these persistent inflows distinguish gradual diversification from a full-scale rejection of the US dollar.

US yields remain significantly higher than global peers, providing a strong financial incentive to hold dollar-denominated assets.

Although the Bank of Japan raised its benchmark rate to 1.25%, it remains well below US levels, indicating that intervention creates immediate market shocks but does not address the underlying interest rate disadvantage, which is why Japan's interventions have not permanently solved the yen's weakness.

Prime Minister Sonate Kaiichi's cabinet, inaugurated on September 17th, 2026, focuses on increasing productive capacity and international competitiveness.

Tokyo states its economic policy is not aimed at manipulating exchange rates, though it retains the ability to intervene if currency movements become disorderly.

A stronger won helps reduce the price of imported commodities and energy, which can ease inflationary pressure on households and companies.

However, excessive appreciation of the won creates its own problems by hurting South Korea's major export sectors, including semiconductors and automobiles.

Seoul aims for currency stability rather than a permanently strong won.

Record exports of $129 billion in September 2026, fueled by AI and computing demand, naturally bring dollars into South Korea, forcing authorities to buy dollars to smooth market adjustments and maintain stability.

Global trade, commodities, and corporate debt remain heavily tethered to the US dollar, demonstrating its enduring dominance in international finance.

Very few alternatives offer the combination of liquidity, size, and financial infrastructure available in dollar markets, which is crucial for central banks that need to trade assets rapidly without destabilizing markets.

This mechanism allows Japan to exchange Treasuries for dollars temporarily, thereby retaining its Treasury securities while avoiding disorderly liquidation.

Japan may no longer be the automatic overseas bond buyer it once was.

Market expectations point to a transition rather than a rupture, with Asian authorities likely to intervene more frequently during periods of extreme exchange rate volatility, and investors expected to diversify portfolios across a wider range of assets. Persistent selling could exert upward pressure on US bond yields.

Despite these interventions, Japan remains a trillion-dollar holder of US Treasuries, even as rising Japanese interest rates are causing some savings to return to domestic assets.