The case for a sovereign bond diversification strategy has rarely been more pressing: persistent tensions in the Persian Gulf, a resurgence in global inflation, and a decisive shift at the US Federal Reserve have combined to make the old approach (gilts, US Treasuries, middle-of-the-road duration, set and forget) look increasingly inadequate.
David Coombs, head of multi-asset investments at Rathbones Asset Management, sets out the case plainly. Benchmark 10-year yields in the US, UK and France have risen by 0.5 to 0.6 percentage points since the start of the year. Germany, traditionally the paragon of fiscal prudence, has seen its own yields climb by 0.4 percentage points, albeit from a considerably lower base. The trigger has been a combination of elevated energy costs flowing from the ongoing Iran conflict and a change in tone from the new Federal Reserve chair, Kevin Warsh.
What Warsh’s communication style means for sovereign bond diversification strategy
Warsh’s ‘less-is-more’ approach to communication has unsettled longer-dated bond markets. Investors have sold longer-dated US bonds on the concern that the Fed may be too slow to raise rates, eventually forcing it to keep rates higher for longer several years hence. Coombs describes that reading as “overegging it,” offering Warsh the benefit of the doubt as the new chair attempts to roll back forward guidance and reduce the Fed’s heavy footprint in markets.
That shift in language has already taken on a formal dimension. At Warsh’s first Federal Open Market Committee meeting in June 2026, the committee stripped the forward-looking language from its policy statement entirely, according to Brookings. For bond investors accustomed to parsing every nuance of Fed guidance, the absence of that language is itself a signal, and one that demands a more active response in fixed-income positioning.
Coombs is not, however, recommending an exit from government bonds. Yields are now high enough to pay a healthy reward for funding governments without requiring excessive duration risk. The argument is for selectivity, not retreat.
Building a broader basket: the practical case for spreading sovereign risk
For roughly the past 18 months, Rathbones has been broadening its sovereign bond holdings well beyond the conventional UK and US pairing. The portfolio now includes euro-denominated debt from smaller countries such as Romania and Portugal, Norwegian government bonds outside the euro framework, Singaporean bonds, and positions in Australian and New Zealand government debt. The rationale is straightforward: with national debts having grown rapidly and public finances under sustained pressure across developed markets, concentration in any single sovereign carries a risk that bond markets are beginning to price more seriously.
Coombs observes that fiscal deficits have been rising across major economies for years, but bond markets have challenged that trajectory only infrequently. That, in his view, is starting to change. After successive demands from pandemic support, geopolitical instability, energy costs, ageing demographics and rising defence spending, sovereign bond markets are becoming more discriminating. Governments’ cost of capital may no longer remain detached from fiscal credibility, particularly where political appetite to address deficits is limited.
The US is cited as a case in point. A sharp rise in US borrowing costs prompted the government to buy back debt in an attempt to push yields lower, a response that, as Coombs notes, only aggravates the underlying problem of spending well beyond its means.
As a result, the Rathbones multi-asset bond portfolios now carry noticeably shorter duration than would have been typical in previous years, reducing overall interest-rate sensitivity without abandoning the asset class. Country selection and sovereign risk differentiation, Coombs argues, will become progressively more important across both fixed income and broader portfolio construction. For long-term income investors, a considered sovereign bond diversification strategy is no longer a refinement; it is the foundation.
