Volume, volatility and information linkages in the stock and option markets

a r t i c l e i n f o This paper examines the relationship between option trading activity and stock market volatility. Although the option market is uniquely suited for trading on volatility information, there is little analysis on how trading activity in this market is linked to stock price volatility. The bulk of the discussion tends to focus on whether trading activity in the stock market is informative about stock volatility. To analyze the information in option trading activity for stock market volatility, a sample of 15 stocks with the highest option trading volume is selected. For each stock, it is noted that the trading activities in the put and call option markets have significant explanatory power for stock market volatility. In addition, the results indicate that the call option trading activity has a stronger impact on stock volatility compared with that of the put options. Our results demonstrate that information and sentiment in the option market is useful for the estimation of stock market volatility. Also, the significance of the effects of option trading activity on stock price volatility is observed to be comparable to that of stock market trading activity. Furthermore, the persistence and asymmetric effects in the volatility of some stocks tend to disappear once option trading activity is taken into account. The information embodied in the trading activity of option and stock markets is an interesting subject studied by many researchers. Assuming markets are complete, option trading should not contain new information for market participants, as options derive their prices from the underlying stocks. However, if markets are incomplete, then this unidirectional relationship may not be true, because informed traders may prefer to trade options instead of the underlying stocks for several reasons: one, option trading involves lower transaction costs and higher financial leverage; and two, investors who have private information about stock price volatility can only make their bet on volatility in the option market (see Chan, Chung, & Fong, 2002). As such, the option trading process may not be redundant. Instead, it could play a significant role in price discovery and even contain information on stock market volatility. The existing literature on whether the option market plays an important role in impounding information into stock prices presents rather mixed evidence. As noted by Amin and Lee (1997), a large proportion of long (or short) positions are initiated in the option market …