NEW YORK (AP) — Standard & Poor’s Ratings Services on Tuesday cut its outlook on Citigroup Inc and Bank of America Corp to “negative” from “stable,” saying bond holders could take a hit if the government steps in again to support banks.

The negative outlook signals the possibility of a future downgrade.

However, S&P affirmed the banks’ investment-grade counterparty credit and debt ratings. S&P’s counterparty credit ratings on Citigroup and Bank of America stand at A and A-1.

S&P defines an A rating as one given to a company that has a “strong capacity” to meet its debt payments over time but is more vulnerable to an economic downturn or a change in circumstances than companies that have the higher ratings of AAA or AA.

S&P credit analysts said the outlook revision on the banks “reflects our increased uncertainty about the US government’s willingness to provide additional extraordinary support to highly systemically important financial institutions in a way that will benefit debt holders.”

S&P said sentiment in Congress regarding any future bailouts is changing, with a goal of reducing taxpayer exposure. The ratings agency cited a recently passed House bill that would penalize bond holders if taxpayer funds are used in company-specific bailouts.

Bank of America, based in Charlotte, North Carolina, and Citigroup, based in New York, were two of the hardest-hit of the big US banks during the credit crisis that peaked in late 2008 and early 2009. The two faced a wave of defaults as consumers fell behind on their loans.

Citi received US$45 billion in government bailout money. It raised US$20 billion in December to help repay the money it received as part of the Troubled Asset Relief Program. The remaining US$25 billion was converted to stock last fall.

Bank of America, meanwhile, also received US$45 billion in loans from TARP, which it repaid in December.

Citigroup shares rose 3 cents to US$3.18 Tuesday, while Bank of America dipped a penny to US$14.47.