The Japanese yen's trade-weighted index has registered a broad decline against key trading partners, measuring the currency's overall loss of purchasing power not just against the U.S. dollar but also the euro and other major currencies. The persistent weakness stems directly from the Bank of Japan's continued ultra-loose monetary policy, which stands in stark contrast to tighter global rate regimes. That policy divergence creates an attractive environment for carry trades, where institutional funds borrow yen at minimal cost to invest in higher-yielding foreign assets.
Global yield curves remain inverted or flat across many major economies, but the BOJ's commitment to yield curve control has kept Japanese government bond yields anchored at low levels. The benchmark 10-year JGB yield hovers near 0.80 percent, well below the U.S. 10-year Treasury yield. That widening differential at the longer end of the curve makes yen-denominated fixed income less attractive for yield-seeking global investors, and the resulting capital outflow from Japan contributes directly to the yen's depreciation.
For Japanese institutional investors, the yen's sustained weakness presents real duration risk challenges. Pension funds and life insurers hold vast foreign bond portfolios. While a weaker yen increases the yen-denominated value of those foreign holdings, the cost of hedging currency exposure rises sharply. Investors must either accept higher hedging costs, which compress net yields, or take on unhedged currency risk — increasing portfolio volatility and eroding returns on an after-hedging basis. That balancing act is critical for managing long-term liabilities.
The Ministry of Finance faces mounting pressure to address the yen's depreciation. Past interventions have provided temporary relief, but the effectiveness of unilateral action is limited when the driver is fundamental policy divergence. Any sustained effort to support the yen would require a shift in BOJ policy — raising short-term rates or allowing JGB yields to rise more freely, a move the central bank has resisted due to concerns about economic stability and debt servicing costs.
A broadly weaker yen raises import costs for Japan, complicating domestic inflation dynamics. Energy and raw material imports become more expensive, potentially pushing up consumer prices — but imported inflation may not translate into sustainable, demand-driven price increases, which is what the BOJ needs to justify its 2 percent inflation mandate. The weakening currency also erodes the value of Japanese assets for foreign buyers, potentially deterring direct investment into the country's equity and bond markets.
