This article analyses the development of FinTech companies in relation to traditional banks in four countries: Denmark, Estonia, the Netherlands and Sweden. Based on approaches drawn from the sociology of markets and field theory, we analyse and theorize about empirical data from secondary sources, official documents and 38 interviews with key actors. Whereas digital technologies have been commonly depicted as a source of disruption for established business models, suggesting that the rise of FinTech leads to competitive upheaval in the financial sector, more recent studies argue that such interpretations are exaggerated. Here, we propose the emergence of a ‘coopetitive’ market ecosystem that combines co-operative and competitive connections between incumbents and challengers who often share the same infrastructure. FinTech firms are shown to function as catalysts in the transformation towards this ecosystem shaped by coopetitive interdependence between the actors.