The Relationship of Insider Trading Announcements, Ownership Structure and Corporate Governance: An Event Study Analysis of Athens Stock Exchange Market Technology Firms

Abstract

In the present paper, the relationship between corporate governance mechanisms of a firm and stock returns triggered by insider trading announcements is examined. Event study methodology has been used to evaluate the influence of 636 insider trading announcements performed by executives of 14 listed firms in the Athens Stock Exchange, that operate in the technology sector, during the period 2007-2013. The relationship between cumulative abnormal stock returns (CARs), caused by the announcements, and corporate governance characteristics, was then examined for different time windows, both for sales and purchases of stocks by insiders. Our findings suggest that insider trading, especially in purchases, performed by CEOs and members of the Boards of Directors, has a significant effect on stock returns in the long run. More specifically concentrated ownership structures and control were found to have a negative/positive effect in abnormal stock returns of the firms only in long-term periods of time following the announcement of purchases/sales.