Global bond yields have climbed to 15-year highs (3.72% on Bloomberg's index as of August 31), driven by rising oil prices, persistent inflation concerns, and expectations of higher US Federal Reserve rates. Major triggers include Fed Chair Kevin Warsh's hawkish rhetoric on August 28 and a smaller-than-expected US bond buyback announcement. Thai analysts attribute the surge partly to shifting investor confidence regarding debt sustainability, large-cap US tech firms' negative free cash flow forcing corporate debt issuance, and reduced Treasury holdings by Japan. Rising borrowing costs pose downside risks to equities.