Distinct clubs or one big party? Global value chain convergence: Supply concentration and susceptibility to supply shocks

Research background: Recent events, such as the COVID-19 pandemic or Russia’s aggression on Ukraine, raise important questions about the stability of supply chains and their resilience to supply shocks. Purpose of the article: This paper investigates convergence clubs in global value chains, focusing on supply concentration measured with the Herfindahl-Hirschman Index. Methods: Using country-sector pairs from the OECD’s ICIO database, we employed the Phillips-Sul (2007) algorithm with the Schnurbus-Haupt-Meier (2017) augmentation to distinguish convergence clubs in the global trade network. Findings & value added: Our main policy-related finding is that there are two main convergence clubs — one covering roughly 80% of all units and the other one close to 20% (the number of divergent sectors is practically negligible). The dominant club is characterised by high and growing concentration, which poses a risk to the trade network, as, over time, it makes trading partners more susceptible to supply-side shocks. Since the global economy has proven to be surprisingly homogenous in terms of concentration patterns, it seems justified that growing concentration could be considered a systemic feature for future theoretical international trade models. Our main methodological finding is that the WIOD database, which is still used as a standard for such analyses, may be misleading due to its limitations. While the results based on the ICIO and WIOD databases do not align, ICIO seems to be superior in terms of coverage.