A violent global bond selloff, marking one of the most aggressive in decades, is underway as renewed US-Iran military action drives oil prices higher, reigniting inflation concerns and sharpening expectations for further interest rate hikes. Yields on major government bonds, including those of the US, Japan, and Australia, have soared to multi-year or even multi-decade highs, putting significant pressure on Asian stock markets and heightening worries about the outlook for risk assets.

The yield on the US 10-year Treasury note climbed to 4.81%, its highest level in nearly three years, edging closer to the critical 5% psychological threshold. Concurrently, the Japanese 10-year government bond yield surpassed 3% for the first time since 1996, while Australia's 10-year yield hit 5.25%, the highest since 2011. Brent crude rose 1% to $95.61 per barrel, diesel prices reached their highest point in over four months, and European gas prices hit levels not seen since 2023.

The sudden shift in market sentiment has directly impacted equities. The MSCI Asia Pacific Index fell 2% to a near one-week low, with South Korea's KOSPI index extending its decline to 4%. Chipmakers SK Hynix and Samsung Electronics both dropped over 4%, and Japan's Nikkei 225 also widened its intraday losses to 3%. European equity futures also point to a weaker open.

"The weak tone in markets this morning is clearly driven by a combination of renewed concerns about the Strait of Hormuz and the backup in global bond yields," said Homin Lee, senior macro strategist at Lombard Odier in Singapore. He maintains a constructive stance on Asia Pacific markets, particularly North Asia, citing "still-solid earnings fundamentals."

Where to Begin

The immediate catalyst for the new wave of selling is the sudden escalation in the Middle East. US military officials confirmed a series of strikes against Iran, which subsequently announced missile attacks on a US air base in Jordan. This exchange broke a period of relative calm that had followed the Trump administration's shift in policy focus from military action to economic pressure on Iran.

Energy markets reacted swiftly. Brent crude climbed 1% to $95.61 per barrel, following a near 6% surge in the previous session, and is heading for a fourth consecutive day of gains. Diesel prices rose to their highest in over four months, and European natural gas prices reached their highest level since 2023, as fears intensify over potential disruptions to energy transport through the Strait of Hormuz.

Climbing energy prices are compounding already elevated inflationary pressures, leading markets to significantly raise expectations for rate hikes by major central banks. Following hawkish comments from Federal Reserve Chair Kevin Warsh at the Jackson Hole symposium last week, market pricing for a September Fed rate hike has risen to about 70%. Swap markets are almost fully pricing in a European Central Bank hike on September 10, assign a 65% probability of an action by the Reserve Bank of Australia on September 29, and have fully priced in a move by the Bank of Japan on September 18. The US 2-year Treasury yield also rose to 4.41%, its highest since January 2025.

Krishna Guha, vice chairman and head of central bank strategy at Evercore ISI, stated that the Fed's primary focus remains on inflation, with oil prices and bond yields holding more weight in policy decisions than employment data. Tim Waterer, chief market analyst at KCM Trade, noted in a report, "The global backup in bond yields has become the dominant narrative for financial markets this week. Higher yields are unhelpful for economic growth and corporate earnings, making it hard to envision risk assets making sustained progress while yields are running away to the upside."

Tech's Debt Spree Adds to Pressure

This bond selloff is not solely driven by geopolitics; massive financing activities in the technology sector are also a significant structural force. Large tech companies are aggressively issuing debt to fund artificial intelligence infrastructure, adding to supply pressures in government bond markets. According to Reuters, Naka Matsuzawa, chief macro strategist at Nomura Securities in Tokyo, pointed out that hyperscalers willing to borrow at higher rates are lifting yields across the curve, shifting the market's focus towards whether economic growth can keep pace with rising interest rates. "An AI-driven productivity jump needs to translate into higher wages," he stated, adding that only then could the economy tolerate higher rates.

Charu Chanana, chief investment strategist at Saxo, warned that bond investors are demanding higher premiums for inflation and fiscal risks, "meaning the selloff can overshoot, and a move to 5% on the US 10-year yield is looking increasingly possible until yields get attractive enough to lure buyers back." Bloomberg strategist Mark Cranfield also pointed out that as Treasury yields return to levels seen in October 2023, investors will recall that yields peaked near 5.02% back then, suggesting "fixed income traders will anticipate targeted buying in that zone if 5% comes into play again."

Nations with Strained Fiscal Positions Are Most Exposed

This global rise in yields poses a particularly severe challenge to sovereign economies already under fiscal strain. The surge in the Japanese 10-year government bond yield beyond 3%, a level not seen in 30 years, has turned market attention towards Prime Minister Sanae Takaichi and her aggressive investment plans. German Bund futures fell to their lowest level since 2011, French OAT futures hit record lows, and UK gilt yields reached their highest since 2008 on Tuesday.

Fred Neumann, chief Asia economist at HSBC, stated that the rise in JGB yields reflects not only investor concern about Japan's fiscal outlook but also global pressures on long-term funding costs. Chanana further noted, "Japan and the UK look most in the front line as higher yields collide with fiscal pressures and monetary policy shifts; France is also vulnerable given its debt trajectory." Rajeev De Mello, global macro portfolio manager at Gama Asset Management, summarized, "Bond yields were already rising, and the US-Iran exchange and its impact on oil prices have made investors even more uneasy about the bond market. At current levels, higher yields act as a clear headwind for Asian equities, especially longer-duration tech stocks."