Given its assomptions, Realist political economy is primarily concerned with how changes in the distribution of international power affect the form and type of international economy, The best known Realist approach to this question is the "theory of hegemonic stability," which holds that an open international economy-that is, one characterized by the free exchange of goods, capital, and services is most likely to exist when a single dominant or hegemonic power is present to stabilize the system and construct a strong regime. For Realists, then, politics underlies nomics. In the pursuit of power, nation-states shape the international economy to best serve their desired ends