Forecasting stock market returns… isn’t that the goal of every investor? Many models exist to fulfill that task: some are simple, others more complex. However, an important aspect of any model is the components it includes. Moreover, model results are preferably easy to analyze, so these components should be simple to understand and easily accessible. In this article, I will introduce the Grinold-Kroner model, which can be used to break down and estimate stock market returns.