Long-term US borrowing costs have climbed to levels unseen since before the global financial crisis, after the Treasury auctioned $25 billion (€21.3 billion) in 30-year bonds at a high yield of 5.058% on Wednesday. The sale came just hours after the US Senate confirmed former Federal Reserve governor Kevin Warsh as the next chairman, succeeding Jerome Powell.
The auction result immediately complicated the backdrop for Warsh's arrival at the central bank, underscoring the pressure facing policymakers as inflation accelerates. At the time of writing on Thursday, US 30-year bonds are trading at 5.02%, while 10-year notes yield 4.44%.
Inflation and the Iran War
US inflation figures released earlier this week showed consumer prices rose 3.8% from April 2025, driven by the 10-week Iran war pushing energy costs higher and distancing inflation from the Federal Reserve's 2% target. Producer price data also pointed to persistent underlying cost pressures across the economy, reinforcing expectations that the central bank may struggle to ease monetary policy quickly.
The main driver of the rise in inflation is the disruption to global energy markets caused by the conflict, which leaves the central bank at the mercy of geopolitics and unable to effectively control the situation. As petrol costs have surged 28%, the war has reshaped inflation hedges, with oil outperforming gold as rates rise.
Rising Treasury yields have broad implications for the economy because they influence borrowing costs on mortgages, corporate debt, and other forms of credit. Higher long-term yields can also increase financing costs for the US government at a time when public debt is nearing $40 trillion (€34.1 trillion).
Investors are increasingly concerned that a combination of resilient economic growth, elevated energy prices, and sustained government borrowing could keep inflationary pressures alive despite two years of restrictive monetary policy. The yield on the benchmark 30-year Treasury bond being auctioned above 5% is a symbolic threshold last reached in 2007 before the onset of the global financial crisis.
Kevin Warsh Inherits a Difficult Policy Environment
Kevin Warsh takes over the Federal Reserve at a delicate moment for the US economy. The former Morgan Stanley banker and Fed governor has previously argued in favour of maintaining the central bank's credibility on inflation, while also signalling support for reforms to the institution's communication strategy and balance sheet policies.
Warsh's confirmation comes as financial markets remain divided over how aggressively the Federal Reserve should respond to persistent inflation pressures. Some investors believe rates may need to stay higher for an extended period, while others warn that maintaining tight monetary conditions for too long could weigh heavily on economic growth and employment.
Analysts stated that Wednesday's Treasury auction illustrated the immediate challenge confronting the incoming Fed chair. Elevated bond yields can help tighten financial conditions without additional rate increases from the central bank, but they can also amplify risks for heavily indebted households, businesses, and the federal government itself.
For European markets, the rise in US yields has already had knock-on effects. The UK 30-year gilt yield hit 1998 highs amid political turmoil, while the Iran conflict reshapes inflation hedges globally. The situation also raises questions about how the European Central Bank will navigate its own monetary policy path, as energy costs and geopolitical tensions continue to influence inflation across the continent.
