Preview: US to sell USD 16bln of 20yr bonds at 18:00BST/13:00EDT

Auction History High Yield: (prev. 4.927%, six-auction avg. 4.877%) Tail: (prev. -1.0bps, six-auction avg. -0.3bps) Bid-to-Cover: (prev. 2.75x, six-auction avg. 2.66x) Dealers: (prev. 8.5%, six-auction avg. 10.1%) Directs: (prev. 19.9%, six-auction avg. 23.9%) Indirects: (prev. 71.6%, six-auction avg. 65.9%) PreviewThe 20-year yield currently trades around 5.15%, comfortably above the previous auction's high yield of 4.927%, offering investors a more attractive outright yield. Treasury yields have risen alongside oil prices following the renewed escalation in the US-Iran conflict, increasing the concession available ahead of the auction.While the higher yield should support demand, the ongoing geopolitical backdrop may also encourage some investors to remain on the sidelines until volatility subsides. That said, market volatility remains relatively contained, with the MOVE Index around 72, only modestly above the 69 level seen at the time of the previous auction. Meanwhile, July's 30-year bond auction was respectable, suggesting investor demand for long-duration Treasuries remains intact despite the recent rise in yields and geopolitical uncertainty. That could provide a constructive backdrop for the 20-year offering.The June 20-year auction was particularly strong, stopping through by 1bp and attracting robust indirect demand, although it took place during a period of relative calm in the Middle East and immediately ahead of the hawkish July FOMC meeting. Since then, the Fed has maintained its more hawkish stance while renewed geopolitical tensions have pushed yields higher. Overall, the combination of higher outright yields and a solid long-end auction backdrop should support demand. However, elevated geopolitical uncertainty may temper investor participation, particularly among those reluctant to add duration while headline risk remains high.