Global Stocks Sink On U.S. Downgrade

Global stock markets have been sinking again today, jolted by the downgrade of the U.S. government's credit rating.

A pledge by the European Central Bank to buy up Italian and Spanish bonds gave some European indexes a boost at the open, but the momentum was short-lived. In Greece, Shares on the Athens Stock Exchange are plunging, with the general price index down 4.8 percent at levels not seen since the mid 1990s.

Dow futures suggest U.S. stocks will join the slide when trading opens on the New York Stock Exchange.