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.

When firms experience financial distress, equity holders may act strategically, forcing concessions from debtholders and paying less than the originally contracted interest payments. This article incorporates strategic debt service in a standard, continuous time asset pricing model, developing simple closed-form expressions for debt and equity values. The authors find that strategic debt service can account for a substantial proportion of the premium on risky corporate debt. They analyze the efficiency implications of strategic debt service, showing that it can eliminate both direct bankruptcy costs and agency costs of debt.

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.

Rating transition matrices for sovereigns are an important input to risk management of portfolios of emerging market credit exposures. They are widely used both in credit portfolio management and to calculate future loss distributions for pricing purposes. However, few sovereigns and almost no low credit quality sovereigns have ratings histories longer than a decade, so estimating such matrices is difficult. This paper shows how one may combine information from sovereign defaults observed over a longer period and a broader set of countries to derive estimates of sovereign transition matrices.

We study the consistency of the credit-risk orderings implicit in ratings and bond market yields. By analyzing errors in term structure estimates for bonds with particular ratings, we show that for significant periods, a quarter of some categories of high credit quality bonds are rated in a manner that is inconsistent with their pricing. Adjusting for economic determinants of spreads (tax, liquidity and risk premiums) and allowing for the dynamic adjustment of ratings and spreads largely eliminates the inconsistencies, however.

The distribution of ratings changes plays a crucial role in many credit risk models. As is well-known, these distributions vary across time and different issuer types. Ignoring such dependencies may lead to inaccurate assessments of credit risk. In this paper, we quantify the dependence of rating transition probabilities on the industry and domicile of the obligor, and on the stage of the business cycle. Employing ordered probit models, we identify the incremental impact of these factors. Our approach gives a clearer picture of which conditioning factors are important than comparing transition matrices estimated from different sub-samples.

When firms experience financial distress, equity holders may act strategically, forcing concessions from debtholders and paying less than the originally‐contracted interest payments. This article incorporates strategic debt service in a standard, continuous time asset pricing model, developing simple closed‐form expressions for debt and equity values. We find that strategic debt service can account for a substantial proportion of the premium on risky corporate debt. We analyze the efficiency implications of strategic debt service, showing that it can eliminate both direct bankruptcy costs and agency costs of debt.

When should regulators close a financially ailing bank? FDIC practice in the US has moved in the direction of early closure. In contrast, banking regulators in Japan continue to follow a more patient approach. This paper analyses a series of models in which closure rules and bailout policies arise endogenously through the interaction of (i) regulators' attempts to minimize discounted, expected bankruptcy costs, and (ii) equity-holders' incentives to recapitalise banks. We characterize subsidy policies for distressed banks that implement socially optimal closure rules at minimum financial cost to regulators and which reduce moral hazard.

This article shows (1) how entry and exit of firms in a competitive industry affect the valuation of securities and optimal capital structure, and (2) how, given a trade-off between tax advantages and agency costs, a firm will optimally adjust its leverage level after it is set up. We derive simple pricing expressions for corporate debt in which the price elasticity of demand for industry output plays a crucial role. When a firm optimally adjusts its leverage over time, we show that total firm value comprises the value of discounted cash flows assuming fixed capital structure, plus a continuum of options for marginal increases in debt.