A further look at linkages between NAFTA equity markets

Recent research finds evidence for convergence among the North American equity markets and argues that this is generated by the North Atlantic Free Trade Accord (NAFTA). In this paper, we re-examine these conclusions and show that the documented cointegration property among the NAFTA equity markets was in fact confined to a sub-period in the late 1990s. We argue that the comovement was caused by the global boom in information technology shares and the resulting change in the sector mix of the value-weighted benchmark indexes used in prior work. We present evidence supporting this alternative hypothesis using an updated data set that includes global industry indexes. Our results have implications for transmission of information across global equity markets and international portfolio diversification.