Comparison of the Ratings: Literature and Practice Overview
The process of rating assignment is similar for different international rating agencies. Frequently, agencies publish their methodologies. However, they do not include detailed information, but rather general directions for rating assessment.
The basic problem for using credit ratings by regulatory bodies and commercial banks is the comparability of the ratings from different agencies. From a practical point of view it is important to compare ratings. So the question is how a relationship between the rating scales can be found when different levels of defaults and expected losses are established.