Multiple directorships and the performance of mergers & acquisitions

• We examine a horizontal S-shaped effect of multiple directorships on M&A performance.
• The results show a three-stage S-shaped impact before the enactment of SOX.
• The mandatory changes by SOX mitigate the negative impact of overboarded directors.
• The results provide a more complete assessment on different levels of directorships.

The question of whether an outside director with multiple board seats creates value for a firm is a subject of continued debate in the corporate governance literature. Dozens of studies have investigated this linkage over the past decades. Unfortunately, the findings generated to date are inconclusive and contradictory. This study reconciles conflicting perspectives by synthesizing the existing insights and knowledge, and develops a new three-stage S-shaped curve proposition. We target firms’ merger and acquisition (M&A) activities to test this argument. The results show a consistent horizontal S-shaped relation between the number of directorships held per director and the wealth creation from corporate M&A investments before the enactment of the Sarbanes–Oxley Act of 2002. However, the negative relation at the highest directorship level turns insignificant in the post-SOX period, suggesting that the mandatory changes by SOX may mitigate the negative impact of overboarded directors. This study contributes to the on-going debate on the performance effect of multiple directorships by providing a more complete assessment of the full range of the advantages and disadvantages across different levels of directorships. The different association patterns found in the pre-/post-SOX periods further highlight the importance of factoring in regulative environmental change when making an inference about the effect of multiple directorships.