Standard & Poor’s, the credit rating agency, has downgraded the investment-grade ratings of 11 top-tier US and European banks and warned it may do so again on concerns over the impact increasing bank industry risk and the deepening global economic slowdown will have on the sector’s performance.

S&P downgraded the credit ratings of Bank of America, Barclays Bank, Citigroup, Credit Suisse, Deutsche Bank, Goldman Sachs, JP Morgan Chase, Morgan Stanley, Royal Bank of Scotland, UBS and Wells Fargo on rising concerns over the banks' earnings potential next year in the wake of the turmoil.