This paper adapts the monopoly capital theoretical approach to the case of large digital platforms. First, we identify the structural drivers of economic power of today’s platforms, i.e. control of data, technology, labour, and value chains, as well as conditioning on government activity. Second, we discuss similarities and discontinuities with respect to the 20th-century transnational corporations. Finally, we focus on policy implications, comparing antitrust regulations and assumptions about the socialisation of data and of digital infrastructure needed to use them.