We investigate the structure of global inter-firm relationships using a unique dataset containing information on customers, suppliers, licensors, licensees and strategic alliances for each of 412,814 major incorporated non-financial firms in the world. We focus on three different networks: customer-supplier network, licensee-licensor network, and strategic alliance network. In/out-degree distribution of these networks follows a Pareto distribution with an exponent of 1.5. The shortest path length on the networks for any pair of firms is around six links. The networks have a scale-free property. We also find that stock price returns tend to be more highly correlated the closer two listed firms are to each other in the networks. This suggests that a non-negligible portion of price fluctuations stems from the propagation of a particular firm's shocks through inter-firm relationships.