The impact of derivative trading on the liquidity of stocks

Abstract

Liquidity is an important factor for smooth trading for all assets including equities traded in the stock markets. Stock exchanges enable buyers and sellers to come together for transaction and in the process reduce the search cost and friction. Higher liquidity motivates more investors to participate in the stock market. Introduction of derivatives of the underlying stock increases the opportunity set available to investors and hence affect the liquidity of the underlying stock.

This study examines the impact of derivative trading on the liquidity of underlying stock using price impact measure of liquidity. The price impact measure of liquidity, which actually measures illiquidity, is given by the average daily ratio of absolute return of the stock to the daily volume over a period of time. The advantage of this measure is that it is based on the observed price changes associated with trades. Two time periods have been chosen to examine the short-term and long-term impact of derivative listing on liquidity of underlying stocks. The first time period is one month pre- and post-listing and the second time period is one year pre- and post-listing.

The results of this study show a shift in the volume from cash market to derivative market, decline in the number of trades, and lower volatility after the introduction of derivative trading. The illiquidity of the stocks also increased in the short run after the introduction of derivative trading and this is definitely not a desirable outcome of introduction of derivative trading. The sample has been divided into four quartiles on the basis of pre-liquidity levels to examine whether the change in liquidity is affected by the pre liquidity levels of the underlying stock. The results show that the impact of derivative trading on long-term liquidity of the market depends on the level of liquidity prior to the introduction of derivative trading. They also show an improvement in long-term liquidity after derivative trading when the liquidity of stocks prior to derivative trading was not high. In other words, derivative listing improved the liquidity of illiquid stocks significantly and served one of the basic objectives of risk management. On the other hand, long-term liquidity was marginally affected if the stocks were already liquid and it is not a matter of concern.