The purpose of this paper is to shed new light on the consistent aggregation problem in input-output systems by making use of some properties of
M-matrices. For example, we show that the stability of a multisectoral dynamic multiplier model is invariant under consistent aggregation, that a consistently aggregated dynamic Leontief model is relatively stable if the original system is stable, and that Gillen and Guccione's Third Proposition can be generalized to cover the case of weighted aggregation.