Excessive leverage and risk taking by large international banks were the main causes of the 2008–09 financial crisis and the ensuing sharp drop in economic activity and employment. World leaders and central bankers promised that it would not happen again and, to this end, undertook to overhaul banking regulation, first and foremost by rectifying Basel prudential rules. This study argues that the new Basel III Accord and the ensuing EU Capital Requirements Directive IV fail to correct the two main shortcomings of international prudential rules: reliance on banks' risk management models for the calculation of capital requirements and the lack of accountability by supervisors. Accordingly, the authors propose the calculation of capital requirements without risk adjustment and creation of a system of mandated action by supervisors modeled on the U.S. framework of Prompt Corrective Action. They also recommend that banks should be required to issue large amounts of debentures that are convertible into equity in order to strengthen market discipline on management and shareholders.