Razionalità e mercati finanziari: proposta di una rete neurale per la Finanza Comportamentale

[6] 1. LA FINANZA COMPORTAMENTALE Per definire la disciplina nel cui alveo si inserisce il presente lavoro ci si avvarrà dell’interessante sintesi fornita da Andrei Shleifer (2000): “At the most general level, behavioral finance is the study of human fallibility in competitive markets. It does not simply deal with an observation that some people are stupid, confused, or biased. This observation is uncontroversial, although understanding the precise nature of biases and confusions is an enormously difficult task. Behavioral finance goes beyond this uncontroversial observation by placing the biased, the stupid, and the confused into competitive financial markets, in which at least some arbitrageurs are fully rational. It then examines what happens to prices and other dimensions of market performance when the different types of investors trade with each other. The answer is that many interesting things do happen. In particular, financial markets in most scenarios are not expected to be efficient. Market efficiency only emerges as an extreme special case, unlikely to hold under plausible circumstances.” La finanza comportamentale, dunque, attraverso l’utilizzo di strumenti mutuati dalla psicologia, dalla sociologia, dalla demografia e dalla storia, oltre naturalmente all’economia, indaga cosa succede nel mercato finanziario al cadere della tragicamente stringente ipotesi di piena razionalità degli operatori. 1.1 Il re è nudo: gli operatori sono irrazionali “There is nothing so dangerous as the pursuit of a rational investment policy in an irrational world”, John Maynard Keynes.