The market position of a company influences its performance. In hazard conditions, all the factors that determine a company's market position and business are exposed to risk. An effective program of enterprise risk management (ERM) decreases the level of risk and improves company performance. ERM is a process that identifies and evaluates all potential losses that can occur in business organizations and selects techniques that can handle and prevent such losses in accordance with the requirements of International Standard ISO 31000. In this paper, seven hypotheses are defined, on the basis of which a theoretical model is developed to examine how different sources of enterprise risk affect the operational performance of Serbian companies and their risk of losing market position.