摘要 : Purpose This study aims to examine the deterrent effect of the Market Abuse Directive (MAD) introduced in the European Union in 2003. The purpose is to evaluate whether the Directive has resulted in significant changes in pre-bid ... 展开 Purpose This study aims to examine the deterrent effect of the Market Abuse Directive (MAD) introduced in the European Union in 2003. The purpose is to evaluate whether the Directive has resulted in significant changes in pre-bid stock price run-ups observed in mergers and acquisitions within the Portuguese, Spanish and Greek stock markets.Design/methodology/approach The study analyzes a sample of 199 mergers and acquisitions in the aforementioned stock markets. The magnitude of pre-bid stock price run-ups is investigated as an indicator of illegal insider trading. The effects of the MAD, toehold positions of bidders and industry similarity between firms involved in the deals are assessed using statistical analysis.Findings The study’s findings indicate that the MAD has been ineffective in deterring investors from trading on non-public information. Pre-announcement price run-ups remain significant, suggesting ongoing illegal insider trading practices. Additionally, the research reveals that pre-bid stock price run-ups tend to be lower when bidders have established a larger toehold position in the target and when the firms involved in the deal belong to the same industry.Originality/value This study contributes to the existing literature by providing empirical evidence on the ineffectiveness of the MAD in deterring illegal insider trading. The findings highlight the limitations of increasing penalties without an effective monitoring system in place. Furthermore, the study identifies additional factors, such as toehold positions and industry similarity, that influence the magnitude of pre-announcement price run-ups in mergers and acquisitions. 收起