%N 4 %X The emergence of global supply chains, that is the organization of production processes in factories that are part of a network of suppliers located in different countries and specialized in specific production phases, brings about a number of major changes in the way the global economy works and interacts. To explore more in detail this phenomenon from a microeconomic perspective, in this paper we provide evidence on Business Groups, that is network-like forms of hierarchical organization between legally autonomous firms spanning both within and across national borders. Exploiting a unique dataset of 270,474 headquarters controlling more than 1,500,000 (domestic and foreign) affiliates in all countries worldwide, we find that business groups account for a significant part of value-added generation in both developed and developing countries, with a prevalence in the latter. In order to characterize their boundaries, we introduce an entropy-like metric able to summarize the hierarchical complexity of a group and its trade-off between exploitation of knowledge as an input across the hierarchy and the associated communication costs. When relating these metrics to the performance of affiliates across business groups, we find a robust (albeit non-linear) positive relationship between a group?s hierarchical complexity and productivity which dominates the already known correlation between vertical integration and productivity. Results are in line with the theoretical framework of knowledge-based hierarchies developed by the literature, in which intangible assets are a complementary input in the production processes. %D 2014 %L eprints2194 %A Carlo Altomonte %A Armando Rungi %K supply chains; hierarchies; business groups; property rights; organization of production; productivity %I Robert Schuman Centre for Advanced Studies. Research Paper RSCAS %T Global supply chains and international competitiveness