The US Treasury has doubled the amount of government debt it buys back, aiming to stabilise the bond market after long-term yields surged to multi-decade highs amid mounting inflation concerns. The move matters because treasury yields underpin borrowing costs across the economy, including mortgages, so a rapid rise threatens to squeeze households and businesses even as the Federal Reserve weighs whether to cut interest rates.

Yields on 10-year, 20-year and 30-year treasuries all hit 20-year highs this week, with the 30-year note reaching its highest level since 2007, before easing following Wednesday's announcement that the policy would "provide greater liquidity support" to the market. The rise had been driven partly by fading hopes of peace between the US and Iran after their ceasefire expired, alongside persistent inflation, which stood at 3.4% in July, and near-record August petrol prices of $4.08 a gallon. New Fed chair Kevin Warsh has yet to signal his stance, while stocks rose modestly after the buyback announcement despite the wider volatility.