US long-term government bonds faced renewed selling pressure on Thursday as Treasury Secretary Scott Bessent's emergency intervention failed to calm investor nerves.

The yield on 30-year Treasury bonds rose 0.07 percentage points to 5.26% in New York morning trading, reversing most of Wednesday's gains following the Treasury's announcement to at least double its purchases of long-term securities from $2bn to $4bn.

Global bond markets mirrored this trend, with 30-year UK gilt yields climbing 0.04 percentage points to 5.82%. Investors remain deeply concerned about the US's mounting public debt burden, which reached a record $40tn on Tuesday, and potential inflation from geopolitical tensions.

Wall Street analysts questioned the effectiveness of the buyback plan, with MUFG calling the unscheduled announcement "lacking a strategic plan" and Columbia Threadneedle's Keith Patton describing it as "minuscule" compared to Fed quantitative easing. Kit Juckes of Société Générale noted that with US publicly held debt at 100% of GDP, foreign investor appetite for US assets will be a growing concern.

The US dollar continued its decline, with the dollar index falling 0.3% on Thursday after a 0.8% drop the previous day.