This paper is aimed at studying the main determinants of people’s choice of a pension fund manager. By using information of the individual saving system (the private system) between 1998 and 2005, and applying panel cointegration techniques, the paper provides evidence in the sense that the rate of return and the employed population are the main determinants of the number of active participants to the different pension fund managers. The average value of the fund, used as a proxy of other variables such as the manager’s capabiliTY to promote their product and contact potential participants, was not significant