We provide a canonical and tractable model of a trade platform enabling buyers and sellers to transact. The platform charges a percentage fee on third-party product sales and decides whether to be "hybrid", like Amazon, by selling its own product. It thereby controls the number of differentiated...

Equilibrium prices behave quite differently if consumers single-purchase (buy either Time Magazine or Newsweek) or if some consumers multi-purchase (buy both). Prices are strategic complements under single-purchase, and increase with magazine quality. In a multi-purchase regime prices are...