This paper examines the admissibility of monetary aggregate groupings for the US over 1993–2001, based upon weak separability. We investigate the impact of retail and commercial demand deposit sweep programs on the separability of monetary asset groupings. Weak separability is tested using the Swofford–Whitney and Fleissig–Whitney tests. We use Varian's measurement error adjustment procedure to eliminate violations of the Generalized Axiom of Revealed Preference (GARP). When funds from both retail and commercial demand deposit sweep programs are placed within checkable deposits, all groupings, narrow and broad, pass GARP and weak separability. For groupings based on conventional money measures, tests tend to favor broad aggregates.

We construct Monetary Services (Divisia) Indexes at various levels of aggregation (the broadest of which is M4) from the late 1940s through 1967 employing methods designed to permit these historical series to be spliced to corresponding series currently published by the Center for Financial Stability (CFS), which begin in 1967. The annualized growth rate of our MSI M2 during 1947 to 1967 generally lies between the growth rates of conventional M1 and M2, while the growth rate of MSI M3 is below that of conventional M3 over the same period. Using spliced series, we find that the velocities of the MSI exhibit gradual upward trends from the late 1940s through 1978, with distinct upward shifts in the late 1970’s and early 1980’s, while the velocity of conventional M3 trends downward between 1953 and 1982. Using a Fourier demand model, we find elastic substitution between M1 and the non-M1 components of MSI M3 up to 1967, but inelastic substitution between bank and thrift deposits.