John Bartko, analyst at Standard & Poor’s, said: “We downgraded BoA one notch because we believe that the economic weakness will persist and that, in turn, earnings pressure for Bank of America will be more intense than we anticipated as recently as 19 December .”

S&P reduced BoA’s counterparty credit rating from A+ to A, with a negative outlook.

Mr Bartko said: “We see some potential for earnings to be substantially worse than we now expect, making further government assistance a potential development.”