Measuring the Liquidity of ETFs: An Application to the European Market

The liquidity of exchange traded funds is of utmost importance for regulators, investors and providers. However, the study of liquidity is still in its infancy. In this work, we show some stylised facts of liquidity statistics (daily/intraday spread, trading volume, etc.). We also propose a new liquidity measure combining these statistics. In this case, liquidity is a power function of the spread where the parameters are determined by actual trading volumes. We also study the relationship between the liquidity of ETFs and the liquidity of the underlying index. We show that they are correlated on a daily basis, but not in terms of intraday frequency. We also define a measure of liquidity improvement and apply it to the EURO STOXX 50 index.