Measuring Money Growth When Financial Markets Are Changing

This paper examines the problem of measuring the growth of a monetary aggregate in the presence of innovations in financial markets and changes in the relationship between individual assets and output. We propose constructing a monetary aggregate so that it is a good leading indicator of nominal GDP; in general the weights on its components vary over time. We investigate two specific procedures: one in which subaggregates discretely switch in and out, and one in which the growth of the aggregate is a time-varying weighted average of the growth of the subaggregates, where the weights follow a random walk. These procedures are used to construct aggregates which potentially augment M2 with stock and/or bond mutual funds. Over 1960-1991, the time-varying aggregates look much like M2, but during 1992-93 the time-varying aggregates outperform M2.