Let me explain the first factor little more in detail. Up to the mid-2000s, the world economy had marked high levels of growth at around 5 percent for four consecutive years.
With hindsight, centering on the United States and Europe, a large credit bubble was formed and  BIS Review 101/2009  1  excesses in financial and economic activity in various aspects emerged during that period. In the area of financial activity, credit and leverage increased substantially as exemplified by the subprime mortgage problem. The economic activity also overheated.