Japan's 30-year bond auction faces a pressure test today, as a global bond market sell-off threatens to add fuel to the fire.

On Thursday, Japan will auction 30-year government bonds, a move that will test the resilience of market investors' demand. Currently, a global bond sell-off has pushed long-term government bond yields to their highest levels in nearly two decades. If the results of this auction are poor, the impact could spill over into global financial markets, further driving up borrowing costs. Meanwhile, concerns stemming from Prime Minister Fumio Kishida's expansionary fiscal policies are exacerbating these pressures domestically. Ahead of Thursday's auction, Japan's 30-year government bond yield fell 7 basis points to 4.095%, further distancing itself from the highest level for this maturity since its introduction in 1999. This drop was attributed to the strengthening of U.S. Treasuries overnight due to falling oil prices. Although the 10-year government bond auction earlier this week was successful, the 30-year maturity faces a tougher testwith global long-term yields remaining high and ultra-long bonds being more sensitive to fiscal conditions and changes in supply and demand. Barclays strategists, including Ayao Ehara, noted in a report: "We expect the overall results to be weak or moderate. Influenced by rising yields last month, current interest rates are at a high level, approaching a reasonable value range based on long-term driving factors, but fiscal concerns continue to pose downward pressure." At the same time, various departments in Japan have submitted record budget requests for the next fiscal year, and the market's focus on the financing methods for new expenditures and the potential scale of government debt issuance has risen sharply. This concern coincides with the benchmark 10-year Japanese government bond yield reaching 3% for the first time in thirty years. Additionally, Bank of Japan Governor Kazuo Ueda hinted that a policy meeting this month may result in an interest rate hike, stating that decisions would be made based on upward price risks. Previously, U.S. Treasury Secretary Scott Bessenet had also commented on the necessity of taking corresponding actions. Strategist Mark Cranfield stated: "The 30-year Japanese government bond auction on Thursday may become another pain point for the U.S. bond market, with the risk of the long-term yield spread between Japan and the U.S. falling below 100 basis points." "We are gradually forming weak auction conditions: the dollar-yen exchange rate has climbed above 160, the G-10 bond markets are under overall pressure, and the Japanese 30-year government bond yield is just a few basis points away from its peak in May. Once it breaks into a higher trading range, the Japan-U.S. yield spread will narrow to below 1%, making Japanese bonds more attractive in relative value and possibly exacerbating the selling pressure on U.S. Treasuries," the strategist added. Market observers pointed out that if the auction results are weak, the shockwaves could go beyond Japan, amplifying the global sell-off and potentially increasing the difficulty for U.S. authorities to curb the rise in long-term government bond yields. Prashant Newnaha, a senior rates strategist for the Asia-Pacific region at TD Securities, stated: "Japanese government bonds have long been a cornerstone of the global fixed income market, but that role has now reversed. Continued selling of Japanese government bonds could trigger a repricing of global fixed income assets." Newnaha also noted that the rise in 30-year yields may "Shift the market's focus back to fiscal policy rather than just monetary policy," emphasizing that Japan's current debt-to-GDP ratio is now significantly higher than during the previous period when 10-year Japanese government bond yields hovered around 3%. However, there are also reasons to expect buying interest. Den Miki, a senior rates strategist at Sumitomo Mitsui Trust Securities, reported that the previous two 30-year government bond auctions (conducted when yields were around 4%) recorded relatively high subscription multiples, and both life insurance and non-life insurance institutions have recently accelerated their buying of ultra-long bonds. Yet she also stated that, given the uncertainty regarding the peak of current yields, investors remain reluctant to extend durations significantly. Den expects this auction's results to fall between average and slightly weak.