Optimal portfolio-consumption choice under stochastic inflation with nominal and indexed bonds

摘要

This research solves the intertemporal portfolio choice problems with and without interim consumption under stochastic inflation. We assume a one-factor nominal interest rate and a one-factor expected inflation rate, implying a two-factor real interest rate in the economy. In contrast to other related research which adopts the one-factor real interest rate model, the inflation-indexed bond is not a redundant asset class even in a complete market. The infinitely risk-averse investor would prefer to invest all her wealth in inflation-indexed bonds maturing at the investment horizon. We also show that, with the two-factor real interest rate model, the consumption-wealth ratio is not determined by the real interest rate alone. The investor's consumption-wealth ratio is also affected by the nominal interest rate and expected inflation rate levels. The capital market is calibrated to U.S. stocks, bonds, and inflation data. The optimal weights show that aggressive investors hold more nominal bonds in order to earn the inflation risk premiums, while conservative investors concentrate on indexed bonds to hedge against the inflation risk.