This article addresses the question of how competition for investments among companies in a certain industry affects their capital structure. The authors develop a new modelling framework that simulates financial variables of a set of firms in a given sector, and uses the framework to analyze how such firms compete for new investments. The leverage of companies affects their flexibility to react to and take advantage of investment opportunities, and the authors show how such flexibility can be optimized to maximize the firm’s growth.As an illustration, they apply the model to a set of European airlines and global pharmaceutical companies. The novelty introduced by this paper is the explicit modelling of the interaction between several companies. The literature on optimal capital structure focuses on individual companies optimizing their capital structure in a world in which the actions of their competitors are exogenous. The authors’ results show how to incorporate the competitive position of the firm as well as the availability of investment opportunities into the capital structure decison.