NEW YORK ( TheStreet) -- Moody's Investor Service has lowered its outlook on three of the big money-center banks, saying financial reform will eventually diminish the benefit of the implied government backstop the institutions have enjoyed since the crisis.

Late Tuesday, the rating agency affirmed its long- and short-term ratings on Bank of America ( BAC), Citigroup ( C) and Wells Fargo ( WFC), but cut its outlook on the ratings to negative from stable, citing "the recent passage of the Dodd-Frank Wall Street Reform and Consumer Protection Act (Dodd-Frank) -- a law that, over time, is expected to result in lower levels of government support for U.S. banks."

Moody's also placed the ratings of 10 regional banks under review for possible downgrade for similar reasons. Companies impacted by this action included BB&T Corp. ( BBT), Capital One ( COF), Fifth Third Bancorp ( FITB), KeyCorp ( KEY), and PNC Financial Services ( PNC), among others.

In a press release announcing its action on Bank of America, Citigroup and Wells Fargo, Moody's estimates that the banks have seen their debt and deposit ratings inflated by between 3 and 5 notches by the implied government support. Moody's added, however, that it was leaving the ratings intact for now because it will take a while for the changes from the legislation to be felt.

"Over the near-term, as a practical matter, Moody's thinks that regulators will continue to face significant obstacles when trying to resolve complex, interconnected, global firms without risking a systemically threatening contraction in credit," the ratings agency said. "Therefore, we continue to believe the current ratings on these three banks are still appropriate."

Moody's gave a 12-to-24 month timeline for how long it will take for its support assumptions to lessen, meaning the banks could see downgrades within that stretch if the ratings agency's view of their own intrinsic strength doesn't keep up with its perception of the impact of less government support.

The ratings agency also noted its rating outlook is already negative for JPMorgan Chase ( JPM), Goldman Sachs ( GS), Morgan Stanley ( MS), and State Street ( STT), which are four of the five other U.S. banks it believes are "systemically important, complex, and interconnected."

The fifth additional bank is Bank of New York Mellon ( BMY), which Moody's still has a stable outlook for, arguing that its ratings don't reflect as much implied government support as those of the other banks at the current time.

Shares of Citigroup closed Tuesday at $4.16, up a penny for the session and 26% year-to-date. Bank of America's stock rose 4 cents to $14.19, putting it down a little less than 6% so far in 2010, while Wells Fargo's stock advanced 1.7% to $28.39 on Tuesday, giving it a gain of 5% on the year.

--Written by Michael Baron in New York.
More on Big Banks
Here Come the Reserves!

Disclosure: TheStreet's editorial policy prohibits staff editors, reporters and analysts from holding positions in any individual stocks.

More from Stocks

Why The FANG Stocks' Dominance May Not Be So Bad For The Market

Why The FANG Stocks' Dominance May Not Be So Bad For The Market

Danica Patrick's Final Race at 2018 Indianapolis 500: What She Thinks About Cars

Danica Patrick's Final Race at 2018 Indianapolis 500: What She Thinks About Cars

At End of May, Investors Signalling They May Stay Away

At End of May, Investors Signalling They May Stay Away

Inside Carnival's Mind Blowing New Horizon Cruise Ship (Video)

Inside Carnival's Mind Blowing New Horizon Cruise Ship (Video)

Neel Kashkari: The Heart of Our Financial System Is More Radioactive Than Ever

Neel Kashkari: The Heart of Our Financial System Is More Radioactive Than Ever