Starting from Directive 2015/2366 on Payment Services in the Internal Market — known as PSD II in the European Union (EU) — countries across the world have or are contemplating a new framework to govern data sharing among different players in the financial market. “Open Banking,” as this trend is called, requires or encourages — depending on the regulatory models adopted in different jurisdictions — banks to share consumer-permissioned banking data with third parties securely, in a form that facilitates its use. The Open Banking initiatives have diffused from the EU, and the UK, to elsewhere. The current Open Banking trend raises analytical questions: is data sharing novel in the banking sector? Before introducing Open Banking, did banks share their data with third parties, and if so, how? On the other hand, however, if data sharing did exist in the pre-Open Banking world, why would governments ever bother to introduce the Open Banking initiatives at all? What are the rationales or concerns justifying such regulatory intervention? What do these regulatory responses look like, and how effective are they in reacting to these concerns?