Credit rating agencies play a critical role in capital markets, guiding the asset allocation of institutional investors as private capital moves freely around the world in search of the best trade-off between risk and return. However, they have also been strongly criticised for failing to spot the Asian crisis in the early 1990s, the Enron, WorldCom and Parmalat collapses in the early 2000s and finally for their ratings of subprime-related structured finance instruments and their role in the current financial crisis