After the financial crisis of 2008, the European Union (‘EU’) not only increased its substantial legislation regarding financial services, but also built up a strong and unified system of financial market supervision. In particular, central surveillance authorities were created. These were given far-reaching competences with regard to substituting dysfunctional national authorities or players in the financial services sector. The three European Economic Area (‘EEA’) and European Free Trade Association (‘EFTA’) States—Iceland, Liechtenstein, and Norway—participate in the EU's internal market through their membership of the EEA. In order to continue participating on an equal footing in the internal market for financial services and to honour their duty to maintain homogeneity, the EEA EFTA States also had to incorporate the new institutional setup regarding financial services supervision. This obligation, however, in particular relating to certain intrusive powers of the new surveillance authorities, collided with some constitutional reservations, above all of the two Nordic EEA EFTA States. This article will show how these conflicting aims could be merged into a system that on the one hand guarantees the unified overall approach needed for strengthened surveillance of the internal market for financial services, and on the other hand safeguards certain constitutional reservations of the EEA EFTA States. It also looks at how third countries that do not (fully) participate in the internal market, such as the United Kingdom and Switzerland, are likely to be treated in this context by the EU.