The US debt machine is getting harder to stabilize

Andjela Radmilac



The US Treasury market is the foundation of the global financial system. It determines mortgage rates, government borrowing costs, corporate lending, and the price of money across the world. For decades, investors treated it as the safest and most stable market on Earth.

But after years of exploding government debt, repeated liquidity scares, and increasingly aggressive Federal Reserve interventions, Wall Street is starting to confront an uncomfortable possibility: the Treasury market may have become too large, too leveraged, and too systemically important to function without constant support.

Now, with debt issuance accelerating and bond yields elevated, a different fear has taken hold inside financial markets: whether the world’s most important market can still absorb America’s borrowing needs without something breaking.

Total marketable Treasury debt has more than doubled since 2018, crossing $30.2 trillion by the end of fiscal year 2025, a year in which the US also ran a $1.8 trillion deficit and, for the first time, paid more than $1 trillion in interest on its publicly held debt, outpacing both defense spending and Medicare in a single budget cycle.

The refinancing calendar adds more pressure: nearly $3 trillion of outstanding debt matured in 2025 alone, all of it requiring fresh buyers, and the pool of buyers that used to handle that load has been steadily thinning.

Foreign central banks have reduced their share of Treasury holdings, and the Federal Reserve, after expanding its balance sheet to $8.5 trillion at the 2022 peak through successive rounds of quantitative easing, has spent the years since trying to shrink it.

That left private markets, including hedge funds, asset managers, individual investors, and increasingly stablecoin issuers, to absorb what sovereign and central bank demand once handled.

When the debt market started needing support

The warning signs had been accumulating for years. The September 2019 repo market freeze was the first real signal that something changed beneath the surface: short-term funding markets seized without warning, and the Fed was forced to inject emergency liquidity within days.

The second and far more alarming episode came in March 2020, when the onset of COVID-19 triggered a mass liquidation of Treasury securities, with institutional investors selling “the world’s safest asset” alongside everything else as they scrambled for cash at any price.

What Brookings Institution researchers later described as the evaporation of bond market liquidity forced the Fed into massive, unprecedented emergency purchases to restore market functioning, interventions that worked but also established a precedent that’s proven difficult to walk back.

Underneath those acute stress events is a structural feature of modern Treasury trading that regulators have grown increasingly worried about. Hedge funds have become central players in what’s known as the cash-futures basis trade, a leveraged arbitrage strategy that exploits tiny price differences between Treasury securities and Treasury futures contracts by holding bond positions funded almost entirely through overnight repo borrowing.

By March 2025, leveraged funds’ notional short Treasury futures positions had exceeded $1 trillion, well above pre-pandemic levels, with the largest funds carrying leverage ratios exceeding 18:1 according to Fed officials.

In November 2025, Fed Governor Lisa Cook formally flagged the arrangement as a systemic vulnerability, warning that positions at this scale make the Treasury market considerably more susceptible to stress.

The April 2025 tariff announcement tested that assessment almost immediately: liquidity deteriorated sharply within days, prompting speculation about Fed intervention before conditions eventually stabilized.

The repo facilities, standing liquidity programs, and targeted purchases used to stabilize those episodes were designed as emergency instruments, but they’ve since become recurring features of the system.

What a strained Treasury market means for everyone

Mortgage rates are where this kind of structural pressure becomes tangible for the average person. The 30-year fixed mortgage rate tracks the 10-year Treasury yield closely, which is why the 10-year’s refusal to fall below 4.3% through much of 2025 and into 2026 kept home loan rates pinned well above 6% even after the Fed cut its benchmark rate three consecutive times.

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