The current study aims at providing empirical evidence concerning the relationship between the ownership structure and performance of the shareholding companies listed on the Amman Stock Exchange (ASE). To measure the ownership structure, used institutional and block holders ownership. The performance is measured by using Tobin's Q (TQ). This study also used a moderating variable which is board independence. To achieve the objectives of the study, this study used the panel data method to analyze data for a sample of 180 companies listed on Amman Stock Exchange (ASE) for the period from 2009 to 2017. The findings show that the ownership structure mechanisms have a significant influence on firm performance measure by (TQ). So, institutional ownership shows a significant positive relationship with (TQ), however, the findings show block holders ownership have a significant negative relationship with (TQ). On another hand, the moderating effect of board independence has a significant positive on the relationship between block holders ownership and (TQ) and has a significant negative on the relationship between institutional ownership and (TQ). The findings of this study confirm empirical research continuing to find a new performance measurement to gain a real form of firm performance. Therefore, the evidence of this study provides empirical evidence to stakeholders, managers and interested parties to support them for its decision.

Previous studies that dealt with corporate governance mechanisms have testified high significant that created some new direction. The current study aims to be engaged in such trends through investigating the relationship between ownership structure as one of the corporate governance mechanisms and performance of the firm with the presence of moderating variable which is CEO duality in developing countries such as Jordan. This study used the panel data method to analyze data for a sample of 180 companies listed on the Amman Stock Exchange (ASE) for the period from 2009 to 2017. Three variables of ownership structure are employed, which are:managerial ownership, government ownership, and family ownership, and moderating variable is CEO duality. The current study used Tobin's Q to estimate the performance of the firm. The findings show that the ownership structure mechanisms have a significant influence on firm performance measured by (TQ). Where managerial ownership and family ownership shows a significant negative relationship with (TQ). While government ownership shows a significant positive relationship with (TQ). On other hands, moderating effect of CEO duality has a significant positive on the relation between family ownership with (TQ), and has a significant negative on the relationship between managerial ownership and government ownership with (TQ). The findings of this study confirm empirical research continuing to find a new performance measurement to gain a real form of firm performance. Therefore, the evidence of this study provides empirical evidence to stakeholders, managers and interested parties to support them for its decision.