In the presence of
redundant assets, of course, the countries’ portfolios are indeterminate. To make our model
a meaningful model of portfolio allocation, we simply need to drop the assumption that the
Arrow-Debreu securities are available for trade and instead to (dynamically) complete the
markets with the countries’ stocks, bonds, and possibly other assets. One, of course, has
to ensure that there are at least as many assets as there are states of the world at each
node; otherwise, our solution approach needs to be modified to explicitly account for market
incompleteness.