The increasing dominance of a small number of ‘big tech’ companies, across a range of critical online markets, has led to growing calls for regulation to promote more competition, and to ensure that market power is not exploited unfairly. New regulatory regimes to this end are now under development in a variety of jurisdictions. Whilst the new German and EU regulatory regimes are the most advanced, there are detailed proposals under discussion in the UK, US and China, whilst in South Korea new regulations have been introduced in relation to the specific area of app stores. This article discusses several questions arising in this context. What problem is pro-competition digital platform regulation trying to solve? Why regulation and not competition law? What are the design challenges involved in developing such regulation? What are the risks arising from diverging regulatory approaches to these global issues and how might these risks be mitigated? And what role can trade policy play?