In 1952 Harry Markowitz published his best-known article, named Portfolio Selection, in the Journal of Finance. For the first time, the concept of mean-variance optimization was introduced, and this served as the foundation of modern portfolio theory and, later, for the Capital Asset Pricing Model (CAPM). Developed as a solution to practical portfolio optimization problems faced at Goldman Sachs, the Black-Litterman method was firstly published in the Journal of Fixed Income in 1991. This approach overcomes the main limitations of the Markowitz model which tends to create concentrated and unstable portfolios that rely excessively on past performance, without comprising investors’ views.