Moody’s Investors Service downgraded the debt ratings of 15 major international banks and securities firms on Thursday, a move that could cost the banks billions of dollars in extra collateral.

U.S banks that were downgraded included:

Bank of America , whose long-term debt rating was cut one notch, to BAA2 from BAA1,

Citigroup , which was cut two notches, to BAA2 from A3,

Goldman Sachs , cut by two notches, to A3 from A1,

JPMorgan , cut by two notches, to A2 from Aa3 and Morgan Stanley , also cut by two notches, to BAA1 from A2.

(Click here for after-hours quotes of these five banks)

All the ratings cuts for the US banks were expected, except for Morgan Stanley, whom some thought would be cut three notches instead of two.

The ratings agency said that the banks were downgraded because their long-term prospects for profitability and growth are shrinking.

The ratings agency said it was especially concerned about banks with significant capital market activities during a time of increased volatility in markets.

A downgrade usually means that it becomes more costly for banks to raise money by selling debt. Investors demand higher interest for riskier debt, which is what the downgrades represent.

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