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Abstract
The Chicago Mercantile Exchange reduced the size of its S&P 500 futures contract when it reduced the multiplier from 500 to 250 and increased the minimum tick from 0.05 to 0.10 on November 3, 1997. This is a rare major change in a very successful contract's specifications. Effects of this change on liquidity and market dynamics are analyzed in both a univariate and a multivariate context. Multiple intervention analysis with various dynamic response functions examines the effects of the split while taking into account several other major market events surrounding it. A multivariate analysis is also used to test the impact of the split using a structural model of liquidity and market dynamics. Empirical findings offer limited support for the hypotheses that smaller contract size resulted in smoother trading, and that more public customers trade the S&P 500 futures contract following its split. No significant and lasting impact on liquidity and market variables is found.





