Arguments for creating a market to allow trading the portfolio of all endowments in the entire world, the "market portfolio," are considered. This world share market would represent a radical innovation, since at the present time only a small fraction of world endowments are traded. Using a...

We construct a new method of decomposing the variance of national incomes into components in such a way as to indicate the most important 'residual' risk-sharing opportunities among peoples of the world. The risk-sharing opportunities we study are nonsystematic risk-sharing opportunities. These...