The superficial exogenous view of market price action is that OPEC news causes price trends. A closer look reveals compelling evidence for an endogenous view of market price action. In the endogenous price trends arise from the dynamic nature of the markets themselves. No external stimulus is needed to induce price trends, and the price trends are cyclical in nature. This brief piece looks at this exogenous versus endogenous issue in terms of OPEC and the 15 year commodity cycle.