Long-term investment with stochastic interest and inflation rates: The need for inflation-indexed bonds

Abstract

We examine the long term investment problem, under stochastic interest and inflation rates and within financial market incompleteness. Four basic financial assets are available on the financial market: a money market account (the cash), a real consumption good, a financial stock index and a bond with constant maturity. In this incomplete framework, we provide the general solution of the expected utility maximization. We compute the monetary loss from not having access to an inflation-indexed bond, in order to be hedged against the inflation risk. We show that this latter one usually reaches high levels (more than 1% per year). Thus, the magnitude of such costs reaches those of management fees or transaction costs. They highlight the significant value of introducing inflation-indexed bonds in the financial markets.