Markets are not defined by who owns them, but by who is forced to act at the margin - and in US Treasuries today, that marginal buyer looks very different from the one most investors still have in mind.

The prevailing narrative feels familiar:

· Geopolitics is driving volatility

· Treasury auctions appear softer

· Foreign central banks are gradually reducing their exposure

Taken at face value, it is easy to interpret this as a story of weakening demand.

But that framing is increasingly misleading, not because the data is wrong, but because it is pointing to the wrong conclusion.

Demand has not disappeared; it has changed form, and most investors are still positioned as if it hasn’t.

 

A change in composition, not a collapse in demand

For much of the past few decades, the Treasury market derived its stability from the nature of its participants. Central banks, sovereign institutions, and liability-driven investors were not trading Treasuries for incremental return. They were holding them as part of broader strategic objectives, whether that be reserve management, currency stability, or long-term asset-liability matching.

As a result, demand was relatively inelastic. Prices moved, but the buyer base didn’t, and that distinction quietly underpinned the system in ways that only become obvious once it starts to shift.

That anchor is no longer as reliable as it once was.

In recent years, hedge funds have absorbed a significant share of net Treasury issuance, a role traditionally held by foreign official institutions.

In its place, a growing share of demand is now driven by hedge funds deploying capital through relative value strategies, basis trades, and funding-sensitive arbitrage. These flows are not anchored to ownership or long-term allocation decisions, but to pricing relationships and the attractiveness of specific trades at a given moment in time.

They are not buying Treasuries because they need to hold them, but because, under current conditions, the trade still makes sense. A subtle but important difference that becomes critical when those conditions change.

 

Liquidity is still there, but it is no longer guaranteed

On most days, nothing looks broken. Market depth appears robust, spreads remain tight, and issuance continues to be absorbed efficiently, reinforcing the perception that liquidity is both abundant and reliable.

That perception, however, rests on an assumption that no longer fully holds.

The stability investors see is conditional on the continuation of the trades that now dominate marginal demand. When funding costs rise, volatility increases, or rate expectations begin to shift, the same participants providing liquidity tend to reduce exposure - often in the same direction, and often at the same time.

What appears stable in calm conditions can therefore behave very differently under pressure. Not because liquidity vanishes outright, but because it becomes far less dependable when it is needed most.

 

A familiar pattern, still misunderstood

We have seen this dynamic before. In March 2020, the Treasury market experienced severe dislocation despite its size and depth, not because demand vanished, but because leveraged participants were forced to unwind positions simultaneously as volatility surged and funding conditions tightened.

More recent episodes, including tariff-driven volatility and geopolitical shocks, have followed a similar pattern, albeit in a less extreme form. Positioning builds gradually in stable environments, often unnoticed, until an external shock disrupts the assumptions underpinning those trades and forces a reassessment.

At that point, the exit becomes crowded, and liquidity, which had appeared deep and structural, reveals itself to be more fragile than expected.

 

Geopolitics is not the cause, but it is the trigger

It is tempting to attribute current market movements directly to geopolitics, but doing so risks overstating the importance of the event itself and understating the vulnerabilities already embedded within the system.

Geopolitical shocks matter because they alter the inputs that drive leveraged strategies, including inflation expectations, interest rate trajectories, and funding conditions. As those variables shift, they directly affect the viability of the trades that now underpin marginal demand.

In that sense, geopolitics does not create instability; it simply exposes how much of it was already present beneath the surface.

 

The implications are structural, not tactical

Treasuries are still widely treated as the foundation of the system:

· the risk-free asset

· the hedge

· the stabiliser

But structurally, they no longer behave in quite the same way.

When pricing becomes more sensitive to liquidity conditions and leveraged positioning, traditional relationships begin to shift.

Yield volatility can rise independently of macro fundamentals, and the negative correlation between equities and bonds - long relied upon in portfolio construction - can weaken at precisely the moments when it is expected to hold.

The market continues to treat Treasuries as the anchor, but in practice, they are increasingly acting as a transmission mechanism through which broader market stress is expressed.

 

A market approaching its next test

The timing of this shift is not insignificant. The US Treasury is expected to refinance roughly $10tn of debt over the coming year, representing a substantial test of market capacity.

In a system that now relies more heavily on price-sensitive and leveraged buyers, the question is no longer simply whether demand exists, but whether it remains aligned when conditions become less favourable.

If the underlying incentives hold, the market will continue to function smoothly. If they begin to break down, the adjustment is unlikely to come from a simple absence of buyers, but rather from a more complex dynamic in which multiple participants step back simultaneously, amplifying the move.

 

Conclusion: Stability, redefined

The US Treasury market remains vast, liquid, and central to the global financial system, but its stability can no longer be understood purely through its size or historical behaviour.

It is increasingly shaped by who is providing liquidity, the conditions under which they operate, and the incentives that drive their positioning. What emerges is a system that still functions effectively, but one in which stability is less structural and more dependent on alignment.

The market, in many ways, still behaves as if that stability is guaranteed.

Increasingly, it is not, and the real risk is not a sudden break, but a gradual shift in behaviour that portfolios have yet to fully account for.

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