Bund yields hit 15-year high as US-Iran conflict lifts oil

Global bond markets split Monday as fresh US-Iran military escalation pushed the 10-year German Bund yield to a 15-year high while Treasury yields retreated from recent peaks.

The 10-year German Bund yield climbed to 3.276 percent, its highest level in 15 years, as fresh US-Iran military escalation lifted oil prices and deepened eurozone inflation concerns, while Treasury yields eased from multi-decade highs.

"Persistent geopolitical uncertainty and elevated oil and gas prices are not helping, alongside the global focus on growing sovereign debt, expectations of renewed supply, and increased political uncertainty after the summer recess," Societe Generale rates strategists wrote in a note.

The 10-year Treasury yield fell from Friday's close, reversing a sharp increase in short-dated yields after Fed Chairman Kevin Warsh made clear at the Jackson Hole symposium that returning inflation to the 2 percent target was his priority, suggesting interest rates might need to rise. The 30-year Treasury yield, which hit a 19-year high of 5.337 percent last week, was last at 5.200 percent, according to Tradeweb. The 10-year gilt yield rose 2.1 basis points to 5.048 percent.

The divergence shows how energy-driven inflation is hitting Europe harder than the US, where the Treasury's decision to double long-end buybacks to at least $4 billion per operation has provided some support. With US federal debt now at $40 trillion and eurozone budget negotiations for 2027 looming, both markets face structural supply pressures that buybacks cannot resolve.

Boston Fed President Susan Collins said on the sidelines of the symposium: "I am open to supporting an increase [in interest rates] if I see conditions as not providing that evidence of continued disinflation that I'm looking for." Warsh has abandoned forward guidance, leaving investors to parse his views on the economy and inflation from the keynote address.

"A buyback does not retire debt and so does not solve the structural problems that have been driving yields up," said Natalia Lojevsky, managing director at CIFC Asset Management.

Impax Asset Management's fixed income CIO Ross Pamphilon said he doesn't expect policy signals from Warsh, who has been consistent in his skepticism of forward guidance. Deficits, term premium and a heavy corporate supply calendar competing with Treasurys have pushed Treasury yields higher over the last two months, he said.

The last time the 10-year Bund yield traded at these levels was during the eurozone debt crisis of 2011, when peripheral spreads widened sharply and the European Central Bank was forced into emergency bond purchases. The current move, driven by energy costs rather than sovereign solvency concerns, carries different implications for the ECB's policy path. Higher energy prices feed directly into eurozone headline inflation, which the ECB has struggled to bring back to target, and complicate the central bank's ability to signal a clear easing trajectory.

For eurozone bonds, negotiations on 2027 budgets will be a key risk, with talks potentially refocusing investor attention on fiscal challenges and political uncertainty, Societe Generale strategists said. Long-dated Treasurys also remained vulnerable as investors continued to voice concerns that the increased buyback of long-end securities was not addressing underlying issues such as the US budget deficit. The buyback program, while doubling to at least $4 billion per operation, remains a liquidity tool rather than a structural fix for the supply-demand imbalance in the long end of the curve.

If oil prices sustain their current trajectory, eurozone headline inflation could re-accelerate, forcing the ECB to delay or reverse any easing cycle. Markets will watch Warsh's subsequent communications and the next round of US inflation data for signals on whether the Fed's tightening bias translates into actual rate increases. For investors, the widening yield gap between US and European sovereign debt creates both relative-value opportunities and duration risk across portfolios, particularly for funds holding long-dated European government bonds. Equity markets face a similar squeeze: higher energy costs pressure corporate margins across transport, manufacturing, and consumer discretionary sectors, while elevated long-end yields raise the discount rate applied to future earnings.

This article is for informational purposes only and does not constitute investment advice.