Japan's Bond Market Turmoil Strains Takaichi's Fiscal Strategy

Japan's government is running short of effective measures to counter a bond market selloff that is pushing debt-financing costs toward levels that could undermine Prime Minister Sanae Takaichi's spending strategy. Analysts say the available tools—such as sporadic cuts to bond issuance or emergency central bank purchases—are only temporary fixes for a market under pressure from persistent inflation and an expansionary fiscal policy.

The benchmark 10-year Japanese government bond yield touched a three-decade high of 2.945% on Tuesday before easing to around 2.89% on Wednesday. Investors are increasingly concerned about Japan's large public debt and inflation risks linked to the Middle East conflict. While government subsidies have kept core inflation below the Bank of Japan's 2% target, the central bank has warned that an inflation overshoot could justify an early rate hike.

The prospect of faster rate increases has led investors to price in a realistic path toward rates reaching 2%, well above earlier expectations of a peak near 1.5%. This repricing is at the heart of the current bond market turbulence.

The yield surge is a critical test for Takaichi's economic approach. Her case for higher spending relies on economic growth outpacing long-term borrowing costs. That assumption would be strained if the 10-year yield exceeds 3% while inflation runs at 2% and real growth hovers around 1%. Government estimates from July project real GDP growth of 0.9% for the current fiscal year and 1.1% the following year.

A sustained move above 3%—the level used in the government's budget assumptions—would push debt-servicing costs beyond the 31 trillion yen currently set aside. Under a baseline scenario assuming the 10-year yield reaches 3.6% in fiscal 2029, those costs would rise to 41 trillion yen. The government has also ruled out spending caps on strategic growth sectors, which could lead to additional debt issuance.

Market participants are watching for signs of official intervention. The finance ministry could make ad hoc cuts to bond issuance or address oversupply concerns at a regular meeting with investors next month. The Bank of Japan could also ramp up bond buying in emergency operations, though a source familiar with its thinking suggests it sees little need to act now, viewing recent yield rises as driven by fundamentals.

Many analysts argue that yields will stay under upward pressure unless the government shifts away from subsidies and tax cuts aimed at easing cost-of-living pressures—measures that can fuel demand and inflation. As one strategist put it, the central bank cannot anchor inflation expectations if fiscal spending continues to add to price pressures. Inflation has become the key risk for bond traders, with market doubts over the government's resolve to combat it at the core of the problem.