S&P waited until after the close of market hours so corporate insiders could finish selling whatever is left of their blue-chip stock holdings. That's how our world really works. Stop kidding yourselves if you think otherwise.
The short term effects are obvious. Banks will raise rates on loan products tied to ten-year Treasury yields, cratering home equity values and eventually forcing more homeowners into foreclosure. Bank of America and Wells Fargo hold plenty of mortgages for deadbeats already, so more inbound jingle mail from impoverished mortgage stuckees will be a nightmare for their servicing desks.
A further stock market selloff on Monday is pretty much assured. The eventual end of the dollar as the world's reserve currency is now assured. The U.S. government is incapable of putting its own house in order. Foreign creditors will now determine the Republic's fate and the ultimate disposition of its citizens' wealth.
Full disclosure: No positions in BAC or WFC at this time.