To stimulate innovation and competition in the digital sector, the European Commission has adopted the Digital Markets Act (DMA), that aims at limiting the gatekeeping power of the biggest actors. For instance, such prevailing platforms may be forced to share with their competitors some, or all, of the data they collected on users that can help improve service quality. This paper proposes a model to analyze the impacts of such a regulation, by comparing (i) a laisser-faire situation where prevailing platforms are free to sell data to newcomer service providers, (ii) the case when platforms can decide to share data but charging newcomers is prohibited, and (iii) a scenario where data sharing is imposed and enforced by the regulator. We investigate the impacts of those scenarios on key metrics like User Welfare, provider revenues, and user demand repartition.