عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In this research has been examined the relationship between liquidity market changes (i.e. bid-ask spread and depth) as a proxy of information asymmetry around quarterly earning announcements and the percentage of independent directors of board, ownership percentage of institutional investors and internal auditing as corporate governance mechanisms in the firms listed in Tehran stock exchange from 1383-1386 (2005-2008). For examine relationships are utilized Pearson correlation test and Mann-Whitney test for internal auditing hypotheses and spearman correlation test and Kendall’s Tau-b test for percentage of independent directors of board and institutional investors hypotheses. Results indicate that there isn’t meaningful relationship between internal auditing and percentage of independent directors of board and information asymmetry. While, information asymmetry has meaningful relationship with institutional investors. Also via comparison changes of bid-ask spread before and after earning announcements by Wilcoxon test is concluded that level of information asymmetry after announcement is more than before it and this subject is consistent with previous researches.