Also, unlike the first two, which are amenable to a single instrument approach, the next two, besides not being necessarily sensitive to policy rates (at least in the desired direction), may need different, even multiple, instruments in different situations. In fact, much of the debate on these objectives revolves around the issues of definition and controllability.
Given this, for my purpose, I will use rather broad definitions for these two objectives. 3. Financial Stability: minimizing the risk that the financial system collapses, thereby disrupting economic activity  4. External Stability: minimizing the risks associated with financing a current account deficit with volatile capital inflows, which may disrupt economic activity.