Futures Down before opening bell May 21

(Market Watch) Standard & Poor's affirmed the U.K.'s credit rating at AAA but lowered its outlook to negative from stable, citing the potential that government debt may equal the country's output. The worse a country's credit rating, the more expensive it is to borrow.
S&P 500 futures down 10.2 points (1.13%) to 829.70 and Nasdaq 100 futures down 13.75 points to 1,378.75. Futures on the Dow Jones Industrial Average fell 85 points to 8310.