“…It should be noted that, although the theoretical models describe the volume-return relationship for individual securities, their implications have also been extensively tested on portfolio data, both using the resulting empirical model similar to our equation (7) on marketwide data (i.e. index returns and volume, e.g., Campbell et al, 1993, Gagnon andKarolyi, 2003) as well as returns and volume of portfolios from a contrarian strategy (Conrad et al, 1994, Coopers, 1999, Parisi and Acevedo, 2001, Gebka, 2005, Alsubaie and Najand, 2009. Similarly, the Sentana and Wadhwani (1992) model of feedback trading has been widely tested on index rather than individual securities" returns (e.g., , Bohl and Siklos, 2008.…”