Essays on central banking and macroprudential policy.

Summary The objective of this thesis, composed of four empirical and theoretical papers, is to study the involvement of central banks in financial stability - defined as a stable and high state of confidence in the ability of the financial system to facilitate the allocation of economic resources, manage risks, and withstand shocks - and to discuss their new macroprudential responsibilities. The global financial crisis has shifted financial regulation and supervision from a microprudential perspective based on the resilience of individual institutions to a macroprudential perspective that takes into account the interactions between financial institutions, the externalities associated with their decisions, and also the effects of the financial cycle on the economic cycle and on financial stability. This thesis analyzes the policy mix of monetary - targeting the business cycle - and macroprudential - targeting the financial cycle - both of which have an impact on price stability and financial conditions. Indeed, these policies operate through transmission channels, some of which are common. Particular attention is paid, beyond macroprudential policy in a heterogeneous monetary union such as the euro area - where countries experience differentiated macroeconomic conditions - in terms of financial and macroeconomic stabilization. Starting from the observation that a single interest rate is adapted to the average of the zone but not to the needs of each country, macroprudential policy could compensate for the absence of an autonomous monetary policy in each country. This would improve the degree of optimality of the monetary zone.