The impact of single stock futures block trade transactions on underlying’s volatility and return : evidence from Stock Exchange of Thailand

Abstract

After the introduction of Single Stock Futures Block trade into the market, the concern of futures trading which is a high leverage product has been being in attention among investors. This paper examines the impact of Block trade trading volume on underlying’s volatility and return by using linear regression model covering 86 stocks from year 2017-2019. For the impact on volatility, this paper use 2 different measurements of volatility to investigate the impact which is Parkinson variance estimator and 30 minutes price historical volatility. The results found a positive relation between Parkinson variance estimator and Block trade trading volume, and also found a positive relation between Parkinson variance estimator and underlying regular trading volume, but there is not enough evidence that Block trade trading volume has a higher impact on underlying’s volatility. While in case of using the second measurement, 30 minutes price historical volatility, we found no relation from both types of trading volume. For the impact on underlying’s daily return, the results found no relation between underlying’s return and change in open interest. The conclusion from this study is that Block trade trading volume is one of the factors making market movement more volatile in a day, but it does not impact daily return implying that force closing position process does not have a significant impact on stock’s return. This paper provides additional information which might be helpful for both regulators, who are enhancing and improving market efficiency, and investors who manage portfolio in spot market.