More generally macroprudential supervision could require actions by two or more supervisory agencies, and there then arises the issue of how best to coordinate their actions. A simple model that would appeal to those who have not worked in bureaucracies would be to require the supervisors to cooperate in developing a strategy to deal with whatever problems arise.
However, cooperation between equals in such an environment is difficult, which is to say inefficient, all the more so in a crisis. It is thus necessary to establish mechanisms to ensure that decisions on macroprudential policy are made sufficiently rapidly and in a way that takes systemic interactions into account.