The market demand for customized products and high delivery capacity is forcing many com-panies to manufacture flexibly and in small lots. This leads to high levels of work in process and capital costs. Companies have to reduce stocks to a minimum, while maintaining an economical system utilization in order to optimize the capital productivity of system and stock. The aim of this doctoral thesis is to develop a model to analyze the capital productivity of the system-stock-bond of single systems and to provide further analysis and improvement potential. Furthermore this thesis focuses on enterprises in the process industry, which represent a highly complex initial situation. To answer the research question a model was developed, in which the model of operation curves and the overall equipment effectiveness are combined. Thus, the effects of improving system efficiency to the ideal stock and the average performance of the system are displayed. In order to deduce improvement activities from the results of this model, an analysis-pyramid is presented. This indicates further analysis, standard strategies and proposals for activities to optimize system efficiency and stock. The implementation of this model is exemplified with a case study conducted in the aluminum industry.