Fitch has become the latest ratings agency to threaten a downgrade of the US' AAA credit rating, warning it will review the rating in August if the country cannot reduce its debt pile.
Markets worldwide suffered on news the US is likely to put an end to its loose monetary policy.
London's leading share index is continuing to build on yesterday's gains despite US GDP growth remaining muted at 1.8% in the first quarter.
European markets climbed this morning on news IMF head Dominique Strauss-Kahn had resigned following sex crime allegations.
The FTSE 100 has opened in positive territory after a commodities bounce-back lifted Wall Street yesterday.
The FTSE has extended yesterday's gains, adding 0.2% in early trading, as strong corporate earnings and upbeat economic data continue to power the index.
Global markets have marginally recovered after yesterday's surprise Standard & Poor's downgrade of the outlook for US debt caused widespread falls.
The FTSE clawed back some of yesterday's losses in early trading despite losses in the US following Standard & Poor's downgrade.
The FTSE 100 opened higher this morning after a sharp fall yesterday on news Japan had been hit by a second earthquake.
World markets have dropped after Japan was struck by a second earthquake in as many months.