Il giorno giovedì 6 giugno alle ore 10.30 presso la Aula Seminari 4026 del DISMEQ, al IV piano dell'edificio U7, il prof. Georg Pflug della Università di Vienna terrà un seminario su Model uncertainty in option pricing: challenging the Black-Scholes formula Abstract It is well known that the validity of the Black-Scholes (BS) formula is restricted to the case, when the Market model is a geometric Brownian motion and therefore admits only one Martingale measure. We consider the situation, when the decision is made on the basis of an acceptability measure (the dual of a risk measure) and the market model is not exactly known, but it is known that it belongs to some ambiguity set of models. We demonstrate that in this case a nonzero bid-ask spread appears, even if the market model is close to the BS model. The bid-ask spread increases with the degree of model uncertainty, but decreases with the acceptability level. The results are based on a duality theorem for ambiguous decisions. Tutti gli interessati sono invitati a partecipare. -- Prof. Fabio Bellini Department of Statistics and Quantitative Methods University of Milano-Bicocca Via Bicocca degli Arcimboldi 8, 20126 Milano 0039-2-64483119 http://scholar.google.it/citations?user=P61L8P4AAAAJ&hl=it