Banks can become illiquid when wholesale funding markets to not function for extended periods of time. Illiquidity quickly transforms into insolvency if liquid assets or cash flows cannot cover banks’ maturing liabilities. Since the 2008–9 global financial crisis, a new financial stability consensus has emerged whereby central banks began implementing unconventional liquidity tools. This chapter comparatively analyzes Hong Kong’s sectoral supervision with the integrated, functional, and Twin Peaks models when implementing unconventional liquidity tools. The macro- and micro-prudential characteristics of unconventional liquidity tools necessitate systemic supervision by central banks and banking supervisors. Effective systemic supervision of unconventional liquidity tools cannot be presumed merely by the presence of a systemic supervisory agency. Underlap can weaken systemic risk objectives and mandates when implementing unconventional liquidity tools because supervisory roles can become uncertain. In this context, Hong Kong’s composite systemic supervisor, the Financial Stability Committee, may not be able to properly coordinate member financial supervisors. Uncertainty can lead to tensions between Financial Stability Committee members, impeding systemic supervisory effectiveness. Tensions coupled with uncertainty can produce macro-prudential and systemic supervisory flaws when managing funding and market liquidity, heightening banking system instability.

This chapter argues that international monetary stability is an underprovided global public good under the current design of the International Monetary System. It proposes to apply the emerging doctrine of Common Concern of Humankind (Common Concern) as a methodological approach. This chapter starts by exploring the concept of monetary stability at the different levels of governance. It is followed by a description of the doctrine of Common Concern. It continues with an analysis of the three-dimensional approach proposed by this doctrine starting with the duty to cooperate in monetary affairs both from a top-down approach (international level of governance) and a bottom-up approach (central banking cooperation). The chapter continues by examining domestic obligations concerning monetary stability with an emphasis on the special role of the central banks and also by examining some cases of unilateral actions and issues of extraterritoriality in the pursuit of monetary stability. Lastly, it offers some remarks on the most controversial aspect of the doctrine that relates to securing compliance with the obligations that may emerge from an accepted Common Concern of international monetary stability.