The storm on Wall Street mainly stems from the asset bubble in the United States. Americans have consumed all their assets, and some even consumed the money they can earn in the future. These consumptions are based on the assumption that American assets don't depreciate and Americans always have jobs, but American house prices fall, American assets shrink and they are insolvent, that is to say, Americans are bankrupt, but the US dollar is an international currency. Most countries in the world have assets denominated in dollars. Americans are smart enough to package their debts and sell them to various countries. When the United States goes bankrupt, these debts will be worthless, and all countries in the world are paying for Americans.