Markets look set for another day of falls as investors fear sovereign debt problems in the US and eurozone could prompt another global crisis.
Fitch has downgraded Greece to CCC status, one notch above default, due to growing concerns private investors do not want to participate in any bailout of the country.
Tim Geithner, the US Treasury secretary, shrugged off warnings from a leading ratings agency about the US public finances as he sought to reassure Wall Street he world's largest economy would be able to maintain its highly-prized AAA rating.
M&G's Jim Leaviss has warned against taking the US' prized AAA rating for granted as the country continues to inject stimulus and defy current European policies of debt reduction.
The UK's credit rating has been revised from negative to stable by S&P, further consolidating its ‘AAA' status and boosting the coalition government's economic plans.
The UK has maintained its AAA credit rating largely thanks to the austerity measures of the coalition government, although it remains vulnerable over the long term.
The head of China's largest credit rating agency has hit out at western counterparts for causing the global financial crisis.
China's leading credit rating agency has stripped the AAA ratings from the UK, US, Germany and France, accusing competitors in the developed world of a bias to the West.
The UK is still in danger of losing its prized AAA rating despite the fiscal tightening measures unveiled by the new coalition Government last month, Standard & Poor's says.
BP has suffered its third downgrade this week, Moody's cutting its credit rating by three notches.