Price and Volume Effects Associated with ELW Issuance in Korea

Abstract

The option pricing model of Black and Scholes (1973) shows that an option contract is redundant in a complete market as it can be completely replicated by its underlying assets and risk free assets. However, in a real world of incomplete markets, many studies have shown that option contracts are not redundant and can affect prices and trade volume of underlying assets as they contribute to the market completeness. Thus, this paper examines whether this holds for ELWs (Equity-Linked Warrants) in Korean stock market, which are well known to have the same function as option contracts. To do this, we analyze the effects of ELW listings on underlying stocks’ prices, trade volume, and volatilities, and test whether ELWs contribute to market completeness. Using the daily trading data of 5,799 ELWs on individual stocks from December 2005 to September 2011, we find that underlying stocks show significantly positive cumulative abnormal returns (CAARs) and abnormal trade volume after ELW listing dates, implying that the ELW listing affects significantly positive effects on prices and trade volume of underlying stocks. The volatility of underlying stocks is significantly decreasing after the ELW listing. The systematic risk measured as beta, however, does not change over the event window. This result indicates that the decrease in volatility of underlying stocks comes from the decrease of unsystematic risks, and the correlations between returns of market index and underlying stocks are increasing after the ELW listing. The result that ELW listing can have significant effects on the underlying market implies that current stock market is incomplete, and thus, it is natural to ask whether ELWs can contribute to market completeness. Using the method suggested by Buraschi and Jackwerth (2001), we examine whether ELWs are necessary to replicate the pricing kernel used in asset pricing. We select risk-free asset, underlying stock and ELW as reference assets to replicate the pricing kernel, and find that the pricing kernel cannot be replicated completely without ELWs. This result implies that ELWs are not redundant financial assets and are necessary to increase the market completeness in Korean stock market.