Analysts said worries over the health of the US debt market could be the motive behind a threat from buyout firm JC Flowers and fellow investors to walk away from a $25.5bn (€18.6bn) acquisition of Sallie Mae, the student loan company.

The buyers, which also include private equity firm Friedman Fleischer & Lowe, Bank of America and JP Morgan Chase, said yesterday that legislative proposals pending before the US House of Representatives and Senate "could result in a failure of the conditions to the closing of the merger to be satisfied."