However, the quantitative asset purchase policies that were used following the crisis proved to be lumpy both to initiate at the ELB and to calibrate over the course of the recovery. This lumpiness tends to create discontinuities in the provision of accommodation that can be costly.
To the extent that the public is uncertain about the conditions that might trigger asset purchases and how long the purchases would be sustained, it undercuts the efficacy of the policy. Similarly, significant frictions associated with the normalization process can arise as the end of the asset purchase program approaches.