The main purpose of this study is to analyze the impact of demographic factors on pension systems and to consider the role that a reserve fund can play in the context of the adjustments needed to balance the accounts of the pension schemes. The study does not deal with the question of the financial management of the reserves. In particular, in the projections presented in the paper, a purely normative assumption has been used for the return on reserves, corresponding to the average return on bonds over the long period. Actually, reserve fund’s investments could turn out to be more profitable than the repayment of government debt, thereby generating leverage. A reserve fund can go overweight in risky (and hence high-yield) assets as long as the disbursement horizon is distant, thus benefiting from attractive returns combined with limited long-term risks. By defining its schedule of income and disbursements, the Pension Reserve Fund can optimize its returns for a given level of risk. However, even with a distant and well-defined disbursement horizon, investment in the Fund would still be riskier than paying down the public debt. Leverage is obviously not contradictory with the Fund’s assigned objective. But this leverage cannot be taken as the prime function of a reserve fund, and its size cannot be precisely calibrated on this basis.