IAS-24 of the International Financial Reporting Standards focuses on the concept and disclosures of related party transactions (RPTs) for a reporting entity. This study examines the interrelationship between RPTs (as disclosed under IAS24), agency theory, ownership structures and firm performance. Our sample includes nonfinancial companies indexed by the KSE-100 of the Pakistan Stock Exchange during 2006–15. To run the regression models, we determine the regression assumptions, normality, heteroskedasticity, autocorrelation and multicollinearity. We investigate the impact of different RPTs, including cash inflows and outflows, whereas other studies generally look at the impact of RPTs on firm performance in totality. The empirical analysis suggests that institutional ownership has a positive, significant impact on firm performance. Related party purchases have a significant, negative impact on performance, resulting in the expropriation of institutional ownership. RPTs that generate revenues have a significant, positive impact on performance, such that institutional ownership has a propping-up effect with respect to the related parties. In practice, institutional ownership leads to strong corporate governance and contributes to firm performance. While other studies find family ownership responsible for the expropriation effect, we argue that institutional ownership has a propping-up and expropriation effect on related parties. Our study also suggests that certain ownership structures lead to weaker corporate governance mechanisms, resulting in greater agency problems. This, in turn, badly affects company performance and leads to the exploitation of minority shareholders.