Asian markets slumped, again, today, after the historic downgrade of the US credit rating. So Japan's Nikkei 225 and Hong Kong's Hang Seng index slid 2.2%, each; China's Shanghai Composite index and South Korea's Kospi sank 3.8%, each; and Singapore's Straits Times index plunged 3.7%. Meanwhile, Standard & Poor's today said that Asian sovereign ratings could face downgrades if global financial markets deteriorate. S&P said its downgrade of US debt wouldn't weigh on Asian government bond ratings in the near term. However, taken together with the weakening sovereign creditworthiness of European nations, the US ratings change does point to an increasingly uncertain and challenging environment ahead, S&P said.And European stock markets gave up initial gains as investors reduced exposure to assets perceived as risky amid escalated worries about the economic outlook. So the key stock indices in France, Germany and UK fell by between 2% and 2.7% in intra-day trade, today. Meanwhile, Finance ministers and central bank governors at the Group of 20 industrialized and developing nations today said they were committed to taking all necessary initiatives in a coordinated way to support financial stability and to foster stronger economic growth. Not specifics were detailed.