This paper provides evidence on the impact of European Banking Union (BU) and the associated Single Supervisory Mechanism (SSM) on the risk disclosure practices of European banks. The onset of BU and the associated rules are considered as an exogenous shock that provides the setting for a natural experiment to analyze the effects of the new supervisory arrangements on bank risk disclosure practices. A Difference-in-Differences approach is adopted, building evidence from the disclosure practices of systemically important banks
supervised by the European Central Bank (ECB) and other banks supervised by national regulators over the period 2012–2017. The main findings are that bank risk disclosure increased overall following BU but there was a weakening of disclosure by SSM-supervised banks relative to banks supervised by national authorities. We also find that the overall positive effect of the BU on bank disclosure is stronger for less profitable banks and in the most troubled economies of the Eurozone (GIPSI countries), while the negative effect on centrally supervised banks is stronger if bank CEOs act also as chairmen (CEO duality). We interpret these findings in light of the fact that the new institutional arrangements for bank supervision under which the ECB relies on local supervisors to collect the information necessary to act gives rise to inefficiencies with respect to the speed and completeness of the information flow between SSM supervised banks and the ECB, which are reflected
in bank disclosure practices.