This paper provides a critical analysis of the subadditivity axiom, which is the key condition for coherent risk measures. Contrary to the subadditivity assumption, bank mergers can create extra risk. We begin with an analysis how a merger affects depositors, junior or senior bank creditors, and...

This paper first provides a simple but very general framework for credit portfolio modellingwhich is based on the distinction between systematic and unsystematic risk. Unsystematicor borrower-specific risk vanishes through diversification in a very large, infinitelyfine-grained portfolio. The...

Value at risk (VaR) is today the standard tool in risk management for banks and other financial institutions. It is defined as the worst loss for a given confidence level: For a confidence level of e.g. p=99%, one is 99% certain that at the end of a chosen risk horizon there will be no greater...

This paper provides a critical analysis of the subadditivity axiom, which is the key condition for coherent risk measures. Contrary to the subadditivity assumption, bank mergers can create extra risk. We begin with an analysis how a merger affects depositors, junior or senior bank creditors, and...

This paper gives a short recapitulation of the constraints for forward and futures prices under the condition that no risk-free profits can be achieved through arbitrage activities.

Abstract Der Beitrag enthält eine einfache Darstellung der beiden wohl bekanntesten Kreditrisikomodelle CreditRisk+ und CreditMetrics und zeigt, wie sich diese Modelle auf eine gemeinsame Grundstruktur zurückführen lassen. Außerdem wird herausgearbeitet, dass kreditnehmerspezifische Risiken...

The aim of this paper is to combine two hitherto unrelated lines of research, namely the granularity adjustment technique for unsystematic credit risk and the theory of coherent risk measures. In theexisting literature, it has always been taken for granted that such a granularity adjustment is...

The granularity adjustment technique is embedded into a general multi-factor model. ... In this paper, a counter-example with negative value of the granularity adjustment is given for the well-known Vasicek (2002) model.

Value at risk (VaR) is today the standard tool in risk management for banks and other financial institutions.