This introduction places in context the papers on credit risk modelling contained in the special issue. We explain why credit risk modelling has become such a focus of interest for practitioners and financial supervisors. Even though, as we explain, the current modelling technologies have significant weaknesses, they offer the possibility of major changes in the ways banks are managed and regulated. The main impediment to greater use of these models, especially by regulators, is the difficulty involved in back-testing the risk measures they produce. We suggest some thoughts on how back-testing and other types of model assessment might be performed.

One of the most important policy issues for financial authorities is to decide at what level average capital charges should be set. The decision may alternatively be expressed as the choice of an appropriate survival probability for representative banks over a horizon such as a year, often termed a “solvency standard”. This article sheds light on the solvency standards implied by current and possible future G10 bank regulation and on the “economic solvency standard” that banks choose themselves by their own capital setting decisions. In particular, we employ a credit risk model to show that the survival probability implied by the 1988 Basel Accord is between 99.0% and 99.9%. We then demonstrate that if a new Basel Accord were calibrated to such a standard, it would not represent a binding constraint on banks' current operations since most banks employ a solvency standard higher than 99.9%. To show this, we employ a statistical analysis of bank ratings adjusted for the impact of official or other support as well as credit risk model calculations. Lastly, we advance a possible explanation for the conservative capital choices made by banks by showing that swap volumes are highly correlated with credit quality for given bank size. This suggests that banks' access to important credit markets like the swaps markets may provide a significant discipline in the choice of solvency standard.

Governments face conflicting objectives in terms of the provision and design of safety nets for banking systems. Safety nets may reduce market discipline and can thus increase the likelihood of a banking crisis. But safety nets are adopted because of the perceived benefits they will confer in either preventing a weak banking system from spilling over into a full-blown crisis or in enabling the government to handle a crisis more effectively. This paper provides evidence on the effects of government safety nets on both these aspects and discusses implications for policy.