Estimating the effect of transaction costs using tick-size as a proxy
A method is proposed for estimating the effect of transaction costs on volatility, using the tick-size as proxy. The method follows three steps: 1) collect only the cases where the tick-size changes from one regime to another, 2) estimate the effect with and without the order book size, and 3) use local data on tick-size and volatility, but instruments from international markets. The first step handles stationarity and dependence. The second step is used to infer the effect of a symmetric transaction cost as tick-size is a revenue and not a cost for liquidity providers. A regression with and without the order book may therefore indicate how much this asymmetry is likely to affect the result. The third step handles endogeneity. The method is applied on intraday data from the Norwegian Stock Exchange (OSE). The results show that both the tick-size and inferred transaction costs seems to have surprisingly little impact on volatility.