I worked as a consultant in the Financial Stability Department (FSD) of the Bank of England for several years (2002–2004). In this paper I reflect on issues relating to the work of such an FSD, starting with the difficulty of defining or measuring ‘financial stability’. Stress tests are commonly used, but, for an FSD, should relate to the system as a whole, not just to individual institutions. FSDs need to assess the probability, virulence and speed of occurrence of potential shocks. There is a need to develop appropriate analytical models. The focus on capital adequacy has diverted attention from concern about having sufficient liquidity.

Banks are linked through the interbank deposit market, participations like syndicated loans and deposit interest rate risk. The similarity in exposures carries the potential for systemic breakdowns. This potential is either strong or weak, depending on whether the linkages remain or vanish asymptotically. It is shown that the linearity of the bank portfolios in the exposures, in combination with a condition on the tails of the marginal distributions of these exposures, determines whether the potential for systemic risk is weak or strong. We show that if the exposures have marginal normal distributions the potential for systemic risk is weak, while if e.g. the Student distributions apply the potential is strong.

The aim of this paper is to explain why cross-sectional estimated migration correlations displayed in the academic and professional literature can be either not consistent, or inefficient, and to discuss alternative approaches. The analysis relies on a model with stochastic migration in which the parameters of interest, that are migration correlations, are precisely defined. The impossibility of estimating consistently the migration correlations from cross-sectional data only is emphasized. We explain how to handle with individual rating histories, how to weight appropriately the cross-sectional estimators and how to estimate efficiently the joint migration probabilities at longer horizons.

Long–short equity strategies allow investors to benefit potentially from both undervalued and overvalued securities. The present study develops a normative portfolio model under the practical conditions that a market-neutral strategy entails. The offsetting long and short equity holdings are established jointly and without any constraints by the underlying market index. While accurately capturing institutional procedures for short selling, the model contains the analytical and economic properties as required for a ranking approach to filter out any undesirable securities under consideration. In view of its practical features, the analysis should be of interest to practitioners for assisting their long–short investment decisions.