Asian stocks tumbled with Tokyo down 2.18 per cent, Shanghai down 3.79 per cent and Seoul down 3.82 per cent.
And there were big losses in oil, while gold, the investors’ safe haven, surged to a record high of 1,709 dollars (1.1886) an ounce.
London’s FTSE 100 went down then up on Monday morning and Paris’s Cac 40 rose and then fell again, while Frankfurt’s Dax was flat.
The euro rose against the dollar after the Standard & Poor announcement, which was responsible for the Asian decline. And the agency warned that it might downgrade again “if the fiscal position of the United States deteriorates further”.
The ECB said it would renew bond purchases after Italy and Spain had announced new measures to control their finances and boost their economies, and France and Germany pushed for full and rapid implementation of a plan to avoid future crises.
And G7 nations said they would take “coordinated action where needed” to guarantee liquidity and financial stability.