Senate Banking chair Johnson cites rating agency's 'irresponsible move.'

Central bank's commitment to purchases is questioned.

Rating agency rebuts S&P downgrade as lawmakers address debt.

Financial turmoil could elicit extended monetary stimulus from Fed.

S&P's affirmation of U.S.'s A1-plus means money funds don't have to sell Treasuries.

'Break them up' strategy entices Kraft, Marathon Oil and ITT.

Norwegian krone and Australian dollars to benefit from U.S., EU problems.

U.S. downgrade likely to be offset by EU debt crisis, slower growth.