Mutual funds typically invest a disproportionately large portion of their portfolio in one industry (main industry). We present a simple theoretical model to demonstrate that better mutual fund managers make larger investments in the important supplier/customer industries related to the main industry. Consistent with our theory, empirical tests on a large sample of mutual funds show that investment in related industries is positively associated with fund performance and plays a more significant role in explaining fund performance than investment in the main industry. Furthermore, the positive relation between main investment and fund performance obtains only when related investment is high.

We rely on a model with incomplete contracts and bargaining power to argue that trade credit (TC) can serve as a commitment device for making relationship-specific investments (RSIs). Unlike existing theories, we explain within a single theoretical framework why TC is affected by firms’ bargaining power and by the specialized nature of transacted goods. Using a large panel of publicly listed firms and innovation-based proxies for RSI, we find strong support for the model’s predictions: TC increases in upstream firm’s RSI and downstream firm’s market power. Endogeneity concerns are addressed by using the passage of innovation-increasing state laws to instrument for RSI and import penetration to instrument for bargaining power.