French and US trading of cross-listed stocks around the period of US decimalization : volume, spreads, and depth effects

We analyze how U.S. decimalization affects stocks cross-listed in France (Euronext) and the U.S. (NYSE). The French stocks examined are much larger than the non-U.S. stocks examined in prior studies of decimalization, and their U.S. trading is likely to be dominated by institutions. So, we explore whether a reduction in depths in the U.S. due to decimalization makes the U.S. market less competitive for institutions trading these French stocks. We find evidence consistent with the above. First, the average NYSE trade size for these stocks relative to that on Euronext declines substantially after decimalization. Second, we categorize individual trades by the number of shares traded. We find that mainly driven by large trades, the NYSE proportion of trading of French firms declines markedly after decimalization. Third, using regression analysis, we find that the decline in the U.S. share of institutional trading volume is significantly positively related with the decline in NYSE depths relative to Euronext, and the decline is greater for French firms. Overall, we find consistent results indicating a migration of institutional order flow in French firms to France after NYSE decimalization. Also, intraday analysis indicates that the institutional volume in both France and the U.S. is greatest when both the markets are open.