Diversifying the risk through portfolio investment

The stock exchange markets are characterized by high dynamics of the investment activity, mainly portfolio investments. The existing relation between yield and risk, on one side, and the portfolio diversification, on the other side, are two basic aspects allowing the investors to build up a portfolio founded on the yield and risk targets which they are aiming. In the frame of this article we have applied the Marcowitz model on a number of portfolios of equities issued by commercial companies listed at the Bucharest Stock Exchange on the main REGS market.