The yield on the 40-year maturity Japanese Government Bond (JGB) has risen sharply to around 3.75%, marking a striking reawakening in a market that many investors had come to view as moribund. This shift reflects a combination of policy evolution, fiscal pressures and changing investor behaviour – all of which are reshaping how Japan is positioned within the global fixed income landscape.
The turning point came in March 2024, when the Bank of Japan (BoJ) began dismantling its yield curve control framework. By removing the cap on 10 year yields, the central bank signalled a meaningful departure from the ultra accommodative stance that had defined its approach for years. Inflation, which has remained above the Bank’s 2% target for more than three and a half years, has proven more resilient than policymakers anticipated. As a result, markets have viewed recent guidance for only modest interest rate increases with some scepticism, questioning whether the Bank’s cautious approach will be sufficient to rein in price pressures. With the gradual withdrawal of the BoJ as the dominant buyer of long term JGBs, the market has lost the stabilising presence that had long suppressed volatility. Private investors are now being asked to absorb additional supply at a time when their appetite is far from assured.
Japan’s debt levels are the highest in the developed world.
Fiscal developments have added another layer of complexity. The government’s ¥18tn spending programme, equivalent to roughly 2% of GDP, comes against a backdrop of already elevated debt levels – the highest in the developed world on a gross basis, even if adjusted figures paint a slightly more moderate picture. These concerns have increasingly been reflected in auction dynamics. Through 2025, demand for 20- and 40-year bonds was notably weak, underscoring investor hesitation. Investor caution has weighed most on longer-dated bonds, with weaker auctions causing wider swings in yields as pricing becomes more market driven.
Compounding these pressures is a shift in the underlying buyer base. As the BoJ reduces its purchases as part of quantitative tightening, domestic banks – once reliable absorbers of long dated JGB supply – have pared back their involvement. This has placed greater reliance on foreign investors, whose enthusiasm has been tempered by a materially weaker yen and concerns over the broader long-term path of government finances. Even with the currency trading at historically cheap levels on a purchasing power basis, overseas demand has remained selective, contributing to an environment in which yields have risen to reflect a more natural balance of risk and reward.
These moves in Japanese yields have not remained isolated. The smaller yield gap between Japanese and US bonds is changing global investment flows and reducing the appeal of borrowing in yen, which had previously offered a convenient source of incremental return. Partial unwinds of these strategies have, at times, strengthened the yen, while exerting downward pressure on foreign bond markets. Japanese institutions, which for years sought higher yields abroad, are now reassessing the attraction of hedged returns overseas relative to those available at home. The valuation gap has narrowed enough that a gradual repatriation of capital is beginning to take shape.
Even with the yen trading at historically cheap levels, overseas demand has remained selective.
The weaker yen has made it more attractive to borrow in yen to invest in riskier assets, particularly global equities. This dynamic carries its own vulnerabilities. A more assertive stance from the BoJ – or even a shift in market expectations – could prompt a sharp reversal of these trades, as seen during bouts of volatility in 2024 and again in early 2025.
Taken together, the rise in Japanese long-term yields represents more than a cyclical adjustment. It marks the early stages of a structural shift – one in which policy intervention is playing a less dominant role, and market forces are returning to the fore. After years of subdued volatility and artificially compressed yields, Japan’s bond market is beginning to reprice in a way that carries consequences across global fixed income, currency markets and risk asset positioning. For investors, this renewed dynamism in a market long considered predictable serves as an important reminder: Japan is once again exerting meaningful influence on the global financial system.
