One of the most salient issues faced by platforms like newspapers and credit card issuers is that users are heterogeneous in the value they bring to other users or to the platform. We develop a model with multi-dimensional heterogeneity where a monopoly platform chooses (price or non-price)...

The externalities advertisers receive from newspaper readers and that operating system users receive from software developers are among the leading features of those “platform” industries. However, they are rarely incorporated into applied models of imperfect competition. We argue this...