For all tose professionals interested in the field of finances, be they economists or not, it is of the most importance to reach a detailed knowledge over the techniques ans instruments that can be used in order to evaluate the risks and the performances of those assets in which one may wish to invest. This article presents a brief yet clear description over the various models that have been developed since 1952, the year in which Harry Markowitz first introduced his portfolio theory. In other words, this essay presents the evolution or the State-of-the-art of the economical Theory in Financing