15 of the world's largest financial institutions have had their credit ratings downgraded by Moodys.
The banks listed included, Goldman Sachs, Barclays, Citigroup, HSBC and Deutsche Bank.
Moody's said, in essence, that the banks' business risked massive losses and that they were exposed to the roiling financial crisis and each other.
Credit Suisse faced the largest downgrade, with its rating slashed three levels from Aa1 to A1.
Four other firms were downgraded by one notch and 10 firms by two notches.
Holding companies of a number of the same banks were also downgraded.
Moody's began their review of the banks in February, and the move was widely anticipated.
In a separate announcement, Moody's also downgraded British bank Lloyds TBS.
Many of the world's largest banks have been locked with governments in a downward spiral since the financial crisis of 2008.
Since then banks have seen the value of their assets slump and their access to private capital shrink, forcing governments and central banks to provide capital and liquidity support that strains public purses.
With governments too poor to provide meaningful economic stimulus and consumers unable or unwilling to spend, banks have seen business dry up and investments, such as loans, turn sour.
The 15 banks downgraded were: Bank of America, Barclays, Citigroup, Credit Suisse, Goldman Sachs, HSBC, JPMorgan Chase, Morgan Stanley, Royal Bank of Scotland, BNP Paribas, Credit Agricole, Deutsche Bank, Royal Bank of Canada, Societe Generale and UBS.
