The Debt Dilemma: How Government Borrowing Can Reshape Global Financial Markets

When governments borrow heavily, the effects do not stay in budget tables. Government bond yields work as the base layer of global pricing, so a shift in what investors demand to lend to Washington, London or Paris changes the cost of mortgages, corporate loans, takeovers and share valuations.

That link is visible now. The US 10-year Treasury yield touched about 5.35% on October 8, a 24-year high, according to Trading Economics, and Forbes reported the 30-year yield at 5.70% on October 7.

Why borrowing moves the market

A government that issues more debt needs more buyers. If demand does not keep pace, it must offer higher yields to attract them. That higher yield becomes the benchmark against which other assets are priced.

The extra return investors require for lending over a long period is called the term premium. CFR senior fellow Rebecca Patterson lists inflation uncertainty, doubts about fiscal sustainability and weaker demand from price-insensitive buyers, such as central banks and pension funds, among its drivers.

She argues a rising term premium is less harmful if it reflects stronger growth expectations, and more harmful when driven by supply and demand shifts or inflation shocks. That is her analysis, not a settled view.

The size of the borrowing

The Congressional Budget Office (CBO) projected in February that the US deficit would reach $1.9 trillion in fiscal 2026, or 5.8% of GDP. It expected debt held by the public to rise from 101% of GDP in 2026 to 120% in 2036, with net interest costs of about 3.3% of GDP this year, just over $1 trillion.

Those forecasts predate the recent sell-off. CBO assumed the 10-year yield would average 4.1% in 2026. With yields now above 5%, interest costs are likely to run higher over time as old debt is refinanced, though that is my inference and not a CBO estimate.

The problem is not only American. The International Monetary Fund (IMF) said in April that global public debt was just under 94% of GDP in 2025 and would reach 100% by 2029, a year earlier than it projected in 2025. It warned that sovereign debt markets are more vulnerable to repricing because of leveraged non-bank investors and a weaker safety premium on US Treasuries.

Competition from corporate borrowers

Governments are not the only large issuers. Forbes, citing Goldman Sachs credit strategist Amanda Lynam, reported AI-related bond supply of an estimated $489 billion this year. That adds to the amount investors must absorb, though it is one factor among several.

Other pressures this autumn include energy-driven inflation. Forbes reported consumer prices up 3.4% over the 12 months to August, with energy up 16.3%. Yields were also rising in other countries, with Japan's 10-year at 3.11% and France's near 5%.

What it does to other markets

Higher government yields reach other markets through several channels.

Deals and listings. Reuters, citing LSEG, reported global M&A fell 41% in the third quarter, with rising borrowing costs cited as a cause. Morgan Stanley's John Collins said higher yields make valuations "a little tougher" at the margins. Several IPOs, including Firmus's ASX listing, have been postponed or withdrawn.

Growth stocks. Companies whose profits lie far in the future are worth less when safer bonds pay more.

Households. Mortgage and loan rates tend to follow long-term yields, although I have not cited specific rates here.

Can policymakers cap the rise?

The US Treasury tried. On August 19 it said it would raise the maximum size of its long-term bond buybacks to at least $4 billion from $2 billion per operation, running from September 9 to November 4, Axios reported. The 30-year yield fell as much as 0.1 percentage point, then largely retraced.

TD Securities' Gennadiy Goldberg called it a "warning shot". Patterson described it as "more signal than substance". The purchases are small relative to a Treasury market of roughly $30 trillion, so their value is mainly symbolic.

A dilemma, not a collapse

The data does not point to a market that has stopped working. Trading Economics reported a strong 10-year auction on October 7 that was "stopped through" by 1.7 basis points, meaning it cleared at a lower yield than the prevailing market. A 30-year auction on October 9 drew solid demand. Fed minutes said the Treasury market was functioning well, though policymakers flagged risks from high yields.

UBS argued that today's yield "reflects a different regime" from 2002, according to Forbes, a reminder that comparisons with past peaks have limits.

The dilemma is that governments need to borrow, while investors are asking for more compensation to lend. The tension is manageable as long as demand holds.

What to watch next

Three measures will show whether the pressure is easing or building: whether long-term auctions keep clearing without concessions, whether Treasury's expanded buybacks continue after November 4, and whether oil prices stay lower, which would ease inflation fears.