“…For example, using datasets containing comprehensive transaction records, Pan and Poteshman (2006) and Chang et al (2009) show that the transactions of different categories of option traders reveal varying degrees of directional information, whilst Ni et al (2008) find that the trading volume of non-market makers contains volatility information. 2 To the best of our knowledge, no study has yet utilized the complete transaction records of an options market to investigate which category of option traders (domestic institutional traders, foreign institutional traders or individuals) possess volatility 1 See Canina and Figlewski (1993), Jorion (1995), Fleming (1998), Blair et al (2001), Poon and Granger (2003), Pong et al (2004), Jiang and Tian (2005), Doran et al (2007), Konstantinidi et al (2008) and Bedendo and Hodges (2009). 2 See also Chan et al (2002), Chakravarty et al (2004), Cao et al (2005) and Chern et al (2008) . information.…”