The monopolisation of data-driven markets endangers competition, and weakens business’s innovative capacity. Regulators on both sides of the Atlantic are largely at one on the need for regulatory action. Most proposals rely on traditional competition-law instruments. The present study, by contrast, makes a far-reaching recommendation: Companies that dominate a data-driven market should be obliged to share certain data. This would give rise to fairer competition and more innovation on the digital market and also fill the idea of data as a commons with life.