The paper generally finds that shares of companies with higher rates of CEO ownership deliver substantial excess returns. As it notes (pages 26-27):

Nevertheless, as an alternative approach, we also examine the returns of a completely passive buy and hold long-only strategy. We consider portfolios that buy into all firms with a CEO who owns more than 10% in the first sample year and portfolios consisting of the top 10% of all firms according to managerial ownership in the first sample year, respectively, without any re-balancing in the following years. The high ownership portfolios always deliver economically large alphas amounting to between 0.84% and 1.15% per month in the value-weighted case and between 0.60% and 0.78% per month in the equal-weighted case. Overall, these results show that even a simple low-cost buy and hold long only strategy based on managerial ownership would have earned substantial abnormal returns.

Some questions I can think of:

 

1. Most notably, contra EMH, why haven’t investors taken advantage of what seems to be a passive means of substantially outperforming the market?
2. Why are the effects of CEO ownership strongest in industries with weak product market competition? After all, if CEO ownership increases incentives for managerial competence (or is otherwise a signal of good management), it seems that this should be more useful for firms in more competitive industries. (One possible explanation is that management is more effectively “priced in” in companies in more competitive industries, as investors view said companies as more risky and needing of scrutiny.)