This report builds on the OECD’s longstanding work measuring government support in agriculture, fossil fuels, fisheries, and more recently in the aluminium value chain in order to estimate producer support and related market distortions in the semiconductor value chain. Results for 21 large firms operating across the semiconductor value chain indicate that total government support has exceeded USD 50 billion over the period 2014-18. Government support provided in the form of below-market debt and equity appears to be particularly large in the context of the semiconductor industry and concentrated in one jurisdiction. Other types of support identified include support for R&D and investment incentives, which benefitted all firms studied in this report. The report also discusses the implications that these findings have for trade rules, and in particular for subsidy disciplines in a context of growing government involvement in semiconductor production and poor transparency of support measures.