Vertical Intra-industry Trade and Fragmentation: An Empirical Examination of the US Auto-parts Industry

The global auto industry has undergone a significant structural transformation in the last two decades as a result of the international fragmentation of production. This increase in cross-border production-sharing activities in the auto industry led to intra-industry trade (IIT) in auto-parts. In this study, the extent of IIT in the US auto-parts industry is examined by decomposing trade into inter-industry trade, vertical IIT and horizontal IIT. Then the development of vertical IIT is analysed as an indicator of international fragmentation between the US and 29 trading partners. Several country-specific hypotheses suggested by the fragmentation literature are tested for the period 1989-2006. The results indicate that a substantial portion of IIT in the US auto-parts industry is vertical IIT, and the econometric results generally support the hypotheses drawn from the theory. In particular, the findings show that the extent of the US vertical IIT is positively correlated with average market size, differences in market size, differences in factor endowments and outward foreign direct investment, while it is negatively correlated with distance and differences in per capita GDP.