Digital technology and big data have transformed the competitive landscape of the banking sector by allowing entrants to offer more effcient, diversifed and affordable services. Incumbent fnancial institutions face increasing competition from new entrants including fntech frms, challenger banks, established tech companies and companies providing third-party data services (e.g., frms providing big data storage and analytics, programming interfaces, etc.). In this new landscape, the availability of, and access to, data has become a key competitive driver. While big data presents new opportunities, the scope of available data and how to govern access to that data pose new challenges for the industry and for competi- tion authorities around the world. Key questions include whether incumbents should be required to share their data with new market entrants; whether, and to what extent, access to and use of big data can be considered to confer market power; and whether and, to what extent, concerns around big data should be considered under competition law as opposed to data protection rules. Any discussion on data access will inevitably be closely linked to the specificities of the market, the type of data, and its use and importance as a tool to compete.