Fixed Fee or Proportional Fee? Contracts in Platform Selling Under Asymmetric Information

ABSTRACT In platform selling, platforms commonly charge third-party sellers a commission fee, which affects sellers’ decision making and platforms’ contract choice. This study explores this choice where a platform privately knows the market size and intends to signal to a seller. We aim to provide researchers and platform-selling practitioners insights into contract and information strategies. The result shows that the fixed-fee contract leads to either a costly or a costless signaling scenario. In costly scenarios, the high-demand platform must downward distort the fixed rent to distinguish itself from the low-demand platform. This distortion results in a different consensus on two players’ contract preference when the commission rate in the proportional-fee contract is exogenous. Under symmetric information, consensus is achieved only on the proportional-fee contract. However, in asymmetric information settings, this consensus may arise on fixed-fee contracts if market uncertainty is high. Furthermore, the comparison of information strategies reveals that players can reach an agreement on both the information-sharing strategy and the proportional-fee contract under certain conditions. When the platform endogenously determines the commission rate, this decision making can also signal demand type, and only the proportional-fee contract leads to a win–win outcome.