This UK OECD Roundtable submission explores the potential effects on competition and consumers that may arise from the use of algorithms in the digital economy and summarizes recent relevant Competition and Markets Authority (‘CMA’) enforcement and research. The ability of algorithms to sort and process huge volumes of data has been key to the development of the online commerce sector, and can generate significant benefits for consumers. However, those algorithms could also have the potential to facilitate business practices that harm competition or consumers. The nature of algorithms and algorithm-driven markets, and the as-yet limited experience of applying competition laws and tools in relation to them, present challenges for competition authorities in effectively detecting, assessing and – where concerns are found – addressing such potential harm. By seeking to deepen its understanding of how algorithms affect competition and consumers, and by targeted use of its full range of competition and consumer powers, the CMA aims to meet those challenges and to ensure that online markets work well for consumers.