“…Finally, the results of the impulse response functions show that the first principal component of trading activity as well as mutual funds' futures trading have a greater impact on the futures-cash basis than other common factors and other investor types. 1 As indicated by Abad and Novales (2005), principal components are defined up to a scale factor, so that the same linear combinations, multiplied by a given real number, or changed in sign, would contain the same information. Thus, in order to compare the VAR results regarding the impact of all types of investors' trading activities on the futures-cash basis, if the regression coefficient of the identified common factor is negative, the Ϫ1 ϫ common factor is used to study the effect of the common factor on the futures-cash basis in VAR analysis.…”