【米10年債は5.2%に】「倍バイバック」は逆効果か／40兆ドル債務に悩むベッセント氏／国防費より高い利払い／ヘッジファンド依存が招く不確実性／年金基金はもはや頼れない
TBS CROSS DIG with Bloomberg
The U.S. Treasury recently sold $25 billion of 30-year bonds at a yield of 5.216%, marking the highest borrowing cost the federal government has paid on 30-year debt since 2001. While the United States remains fully capable of selling its sovereign debt, a fundamental shift in market dynamics is altering who finances this borrowing and how much compensation those investors demand. As the total U.S. national debt crossed the $40 trillion milestone, the rising cost of servicing long-term debt has transformed from a low-cost routine into a major fiscal and economic challenge.
A Growing Refinancing Burden in a High-Rate Era
The surge in borrowing costs means that taxpayers are funding significantly higher interest rates to bondholders compared to recent years. For most of the past two decades, U.S. and global interest rates remained depressed, making continuous borrowing relatively inexpensive. However, as post-pandemic inflation surged, government borrowing costs rose worldwide.
Because bond prices and yields move inversely, widespread bond selling by investors directly drove up the government's borrowing expenses. This pressure has become particularly pronounced at the long end of the maturity curve. Investors committing capital for 30 years face elevated long-term risks, leading them to demand higher compensation to offset that exposure. For Treasury Secretary Scott Bessent, this mounting rate environment poses an ongoing operational challenge: as older bonds continually mature, the Treasury must repeatedly return to the market to issue new debt and refinance existing obligations at whatever prevailing rates the market dictates.
The Disappearing Anchor: From Central Banks to Hedge Funds
The structure of the Treasury buyer base is undergoing a significant transition. Historically, the U.S. government could count on a steady, dependable group of buyers composed of the Federal Reserve, foreign central banks, and long-term institutional investors. Central banks, in particular, often purchase Treasuries for strategic reserve or policy reasons unrelated to investment returns, continuing to buy even when prices fall.
As the sheer volume of issuance has grown, the government has become increasingly reliant on hedge funds. Unlike traditional anchor buyers, hedge funds operate across much shorter time horizons, are far more price-sensitive, and are willing to exit the market when conditions turn unfavorable.
Simultaneously, pension funds—the traditional natural buyer for long-dated debt—have been withdrawing from their historical role. Under older defined-benefit systems, where funds promised set payouts to retirees, pensions deliberately acquired long-dated government debt to match their long-term liabilities. In recent years, pensions have shifted toward return-based market models, reducing their structural demand for long-maturity sovereign paper. Consequently, the Treasury has been forced to seek out alternative investors at shorter maturities, such as money market funds, which typically lend capital for a maximum of one year. This creates a structural mismatch: just as the government faces vast refinancing needs that require multi-decade capital commitments, the pool of patient, long-term buyers is shrinking.
The Policy Shift: Buybacks and Unintended Market Friction
In response to these liquidity and maturity pressures, Treasury Secretary Scott Bessent altered strategy in August. The Treasury announced an increase in buybacks of long-dated government bonds, funded through the issuance of shorter-maturity debt. The stated rationale was to provide enhanced liquidity support to the market.
However, the maneuver did not immediately resolve the underlying tension. Market participants expressed concern over the predictability of Treasury policy. When sovereign debt management deviates from established patterns and becomes perceived as unpredictable, bond investors may demand an additional risk premium to compensate for that heightened policy uncertainty.
Broad Economic Ramifications and the Fiscal Reality
The behavior of the Treasury market has direct consequences across the broader economy because U.S. government bond yields serve as the benchmark for global asset pricing. Shifts in these yields dictate the valuation of equities, corporate debt, and residential mortgages.
The repercussions of elevated long-term yields extend directly to commercial landlords refinancing real estate portfolios, property developers evaluating the economic viability of projects, and corporations rolling over debt originally secured during years of cheap borrowing.
The impact on the federal government's own balance sheet is equally stark. In August, U.S. interest payments to bondholders reached a record $85 billion. As a result, the United States now spends more on debt service than it allocates to defense spending. The clear trajectory indicated by these dynamics is that elevated borrowing costs are poised to remain higher for longer across governments, businesses, and consumers globally.