News dissemination online is driven by three gatekeeping logics: the gatekeeping logic of the news media (publishing), the gatekeeping logic of social actors (sharing), and the gatekeeping logic of platform algorithms (spreading), each guided by different values and with a different relationship to content. Using a reverse engineering approach, this study applies a 2015 dataset to empirically explore how a Facebook algorithm changed the overall composition of the news users saw, highlighting the ongoing issue of how the different gates and associated gatekeeping logics – especially that of platforms – influence news distribution. In contrast to previous studies, we find the relationship between news properties and the distribution of news online to be non-linear. Results point to Facebook's role in the overall composition of online news, both directly and in interaction with other gatekeepers. As news stories become more widely spread online, algorithmic logics take precedence over user behaviour and preferences.