The Moody's financial services company has cut the credit ratings of three key American banks.

Moody's said Wednesday it cut the ratings for Bank of America, Wells Fargo and Citigroup because it thinks it is less likely than in the past that the U.S. government would bail them out if they got in financial trouble.

The ratings company said it is more likely now than during the height of the recession in 2008 and 2009 that the government would allow major financial institutions to fail. That would cost shareholders billions of dollars of their investment money, but avoid putting taxpayer money at risk.

During the height of the recent recession, the U.S. government moved quickly to support major financial institutions and some manufacturers, pouring hundreds of billions of dollars into the effort to keep them from collapsing. Much of the money — but not all — has since been repaid to the U.S. Treasury.

Moody's said that it now believes that the U.S. commitment to save “systemically important” financial institutions has diminished, in part because the fear of a widespread economic collapse has lessened, even though the U.S. economy is close to stalling.

Moody's cut Bank of America's long-term debt rating two notches , downgraded Wells Fargo's debt one notch and trimmed Citigroup's short-term credit rating one notch .