The question whether a relationship between insider ownership - i. e. direct shareholdings of managers in their firms - and corporate performance exists increasingly attracts attention in academia as well as in investment practice. The work on hand is an important contribution to this strand of corporate governance research especially as most of the relevant studies refer to Anglo-Saxon capital markets. This study investigates the relationship between insider ownership and corporate performance on the basis of a new and unique data set of German corporations. The results of this study are very interesting from both an academic and practical perspective. They provide evidence that the development of investment strategies should not disregard companies' ownership structures and shed new light on the role of insider ownership as a corporate governance mechanism. Finally, this work constitutes the first comprehensive overview on the development of shareholder structures of German listed stock corporations.