With the establishment of the troika institutions during the Euro crisis, issues related to possibilities for control and constraint of these institutions, as well as their accountability, became prominent. This contribution analyses the accountability of the troika institutions, that is, the extent to which agents and trustees are controlled at different levels by their principals or beneficiaries. Specifically, I distinguish between a delegation and a fiduciary mode of accountability in EU governance. While the delegation mode is characterised by formal hierarchical, supervisory and legal control mechanisms, the fiduciary mode is marked by informal peer organisations and public reputational mechanisms. In order to illustrate these two modes of accountability, this article examines a delegation relation (European Commission and Council of Ministers) and a fiduciary relation (European Central Bank and Eurozone-Member States) during the financial bailout assistance programmes.