The volume collects a selection of papers of the 21st EURO Working Group on Financial Modelling. The papers in this book provide a representative, though not complete sample of the current scienitific activity in the field of quantitative finance. Such activity is not only theoretical but also practical, because it tries to combine theoretic analyses with empirical evidence. The topics deal with corporate finance, asset price analysis, portfolio management, decision theory, international exchange markets and financial derivatives. It is important to note the presence of algorithms, methods and models, helpful in the real activity of a decision maker, as performance evaluations and scenarios identifications in portfolio models, how to measure bank efficiency, and how to realize an efficient diversification of international investments, etc.