ARHIVELE OLTENIEI - Universitatea din Craiova

344Gheorghe Bică, Mădălina Constantinescuheard so much news? It is possible that a trader works with the surest news andto trust his own point of view.■ Rumours and rational behaviourPeople talk about the inexplicable movements of prices, caused byirrational participants on the markets so that the rumours are amplified onfinancial markets. Until the rationality is a key-word in political economy and infinancial theory, it is necessary that we evaluate that the rumours are true orfalse. The term rationality derives from the Latin ratio which means “reason”. Arational behaviour is that attitude that permits us to take rational decisions.In political economy, the rational behaviour permits to someone to take adecision that maximize the personal utility of a person which corresponds withthe classic portrait of homo economicus. But, the people, in reality, do notactivate always like a homo economicus. So, that kind of definition does not helpus to discover what a rational behaviour is. Maybe if we take the opposite of thisconcept and we define the irrational behaviour and that will help us. Accordingto Brockhaus Encyclopdia, irrationality is defined as “incomprehensible mind”.Comparative to rationality, mind is here linked with rationality. So, if an actionis incomprehensible by me, that action is indeed non-rational.■ Rationality in the financial marketsThinking that the participants on the financial markets activate at least in aprocedural manner that is rational and taking as examples past movements ofprices, especially on the actions markets in the last years, this theory must beupdated integrally 6 . The participants on the financial markets activate rationallyso that they have an advantage, so that their decision take into account theavailable information and the activity of the other participants. The actions helpthem to attain their precise aim. We suppose that to analyse rational behaviouron the financial market that the investors accept the price. This not a criticalhypothesis, at least on a big market, capitalised, with liquid share, it is notpossible that just one participant controls and leads transactional prices for along period of time.The price, which is a hazardous result of the all intentional actions, is themost important thing that interests all the participants. They have to adjust theirpositions to the hazardous result. This thing happens, for example, if they adjusttheir relative portfolio to a benchmark or if they replay to the last news, like therumours. As a result of evaluating proper positions according to the last news,hazardous price, the positions that must be revaluated and adjusted. The reasonthat this thinks do not happens simultaneously is the asymmetry of information. Soall the participants have access to the same percent of information which must beinterpreted and evaluated in a different way. Thus, the behaviour of one participantis rational and “socially influenced”. Their position is adjusted according to the6 R. Shiller, Irrational Exuberance, Princeton University Press, Princeton, 2000.