This note was prepared by Ania Thiemann of the OECD Competition Division. Helpful comments and review were provided by Ori Schwartz, Antonio Capobianco, Richard May and Connor Hogg, also of the OECD Competition Division. This paper is part of the OECD Horizontal Project on ‘Thriving with AI: Empowering Economies, Societies and Citizens.’ It has also benefited from useful comments from colleagues in the OECD Directorate for Science Technology and Innovation, particularly Julia Carro at the Digital Policy Co-ordination Team as well as Luis Aranda and Jeff Mollins from the Artificial Intelligence and Emerging Digital Technologies Division. The note was prepared to serve as background material for discussions on “Competition and Artificial Intelligence” taking place at the December 2025 session of the 24th OECD Global Forum on Competition, and in particular for the session on “Artificial intelligence and competitive dynamics in downstream markets”.