The real story is that S&P thinks downgrading the US debt will provide political cover against investigations into their role in the mortgage securities debacle

The real story is that S&P thinks downgrading the US debt will provide political cover against investigations into their role in the mortgage securities debacle by the SEC and Justice. They were determined to downgrade no matter what. Their original justification is the US didn't make their $4 trillion cut target. When Treasury showed them a $2 trillion dollar error in their arithmetic, they changed the justification to political gridlock. Time for a perp walk.