An overlapping generations model of social security with labor and capital productivity shocks and demographic shocks is studied.

Un large debat s'est ouvert dans les pays occidentaux pour modifier les systemes de retraite bases sur la repartition. Gravement touches par l'evolution demographique, certains leur imputent aussi des effets distortionnaires sur l'offre de travail et une desincitation a l'epargne des menages...

In a static exchange economy, when all the endowments are issued as securities on a stock exchange, Pareto optimal allocations may be reached by trading options on the market index (see Breeden and Litzenberger (1978)). We extend this result when some of the risks cannot be exchanged on the...