This is a technical guide on how to model operational risk, with practical advice on how to set up an AMA programme that supports the modelling and quantification goals of a financial institution. The book focuses on practical solutions to modelling issues. It helps the reader set up a strong programme with quantification in mind, providing good quality information for modelling, in order to deliver the numbers needed for regulatory approval, and deliver value to their business lines. It presents many complex topics in a highly accessible manner. Five comprehensive sections guide the reader through the following key topics: the AMA framework - outlines a general approach to constructing an advanced measurement approach framework within a bank - the basis upon which any op risk model is built. It provides do's and don'ts as well as step-by step guidance on how best to achieve the goals of an op risk programme. It covers areas, such as data selection, granularity, correlation, and diversification. Modelling basics - covers the fundamentals of operational risk modelling with discussion of general concepts, a study of Citigroup's own approach, as well as analysis of the main mathematical models regularly used to analyse loss data. Modelling challenges - shows you how models can be adjusted to overcome limitations in the underlying data. It includes practical guidance on loss data capture, the effect of data gaps on parameter estimates, expected and unexpected loss calculations and the use of extreme value theory to help mitigate some of the data problems associated with operational risk modelling. These complex topics are presented in an accessible manner, with plenty of thorough explanation to help digest and implement the content. Alternative modelling approaches - this section gives a general framework for thinking about qualitative elements and their role in modelling - including scenario analysis, key risk indicators, and how to overcome the challenges in the modelling of less tangible risks, such as technology risk. Comparative views of implementation - to help gain a broader understanding of how op risk practitioners around the world are implementing their op risk solutions - the final section contains an overview of an op risk framework at a US bank, plus implementation studies from Spain and Germany. The German study unveils the results of a major industry survey, outlining "real world" practices in financial services firms, including the strengths and shortcomings of firms' approaches to solving key op risk challenges.