S&P said the changes reflected its assessment that volatility will remain in the financial sector and the industry is expected to face tighter regulatory oversight. S&P also said loan losses, which have plagued the industry for more than a year, are likely to continue to increase and could grow beyond expectations.

BB&T, Capital One Financial, Regions Financial and Wells Fargo were among the largest banks that saw their ratings cut by S&P.

Widescale changes to the industry because of the credit crisis and ongoing recession will dramatically alter the banking landscape, S&P credit analyst Rodrigo Quintanilla said in a release.

"We believe the banking industry is undergoing a structural transformation that may include radical changes with permanent repercussions," Quintanilla said. "Financial institutions are now shedding balance-sheet risk and altering funding profiles and strategies for the marketplace's new reality. Such a transition period justifies lower ratings as industry players implement changes."

S&P did note that recent capital raising efforts in the sector will help defray some of the losses banks are facing.