The yield on the 30-year US Treasury bond has climbed to its highest point in nearly 20 years, fueled by investor concerns over the surging size of US government debt, a significant increase in long-term bond supply, and inflation that has persistently exceeded the Federal Reserve's target over the past five years.

On Monday, the 30-year yield rose 3 basis points to 5.29%, marking its highest level since 2007 and edging closer to the 5.44% peak recorded during the early stages of the global financial crisis.

The upward movement in long-term yields is raising the US government's borrowing costs. As public debt expands and inflation remains elevated, short-term interest rates could stay higher for an extended period, prompting investors to demand a greater risk premium.

Anshul Pradhan, head of US rates strategy at Barclays, noted: "We have consistently argued against betting against the long-end selloff, and we continue to hold that view. A rebound in long-dated bonds would require several factors to align simultaneously, including an improvement in fiscal conditions, a slowdown in AI-related bond issuance, adjustments in the US Treasury's issuance strategy, and sustained weakness in economic data."

Monday's trading extended the previous week's decline. Last week, the US Treasury was forced to auction $25 billion in 30-year new bonds at a yield of 5.216%, the highest award yield for such sales since 2001. The day before, the 10-year note's auction yield also rose to its highest level since 2007.

Weakening US economic data has also intensified the divergence in performance across different maturities, pushing the yield curve steeper. So far this month, the 30-year yield has surged more than 13 basis points, while the 2-year yield has dropped 12 basis points.

Investors are now closely watching whether the recent trend in long-term yields will persist, as fiscal policy and inflation dynamics continue to shape market expectations for the trajectory of government borrowing and monetary policy.