Online Truthful Mechanisms for Multi-sided Markets

The study of mechanisms for multi-sided markets has received an increasingly growing attention from the research community, and is motivated by the numerous examples of such markets on the web and in electronic commerce, including: online advertising exchanges, stock exchanges, business-to-business commerce and bandwidth allocation. Many of these examples represent dynamic and uncertain environments, and thus, require, in fact, online mechanisms. Unfortunately, as far as we know, no previously published online mechanism for a multi-sided market (or even for a double-sided market) has managed to (approximately) maximize the gain from trade, while guaranteeing desirable economic properties such as incentivizing truthfulness, voluntary participation and avoiding budget deficit. In this work we present the first online mechanism for a multi-sided market which has the above properties. Our mechanism is designed for a market setting suggested by [Feldman and Gonen (2016)]; which is motivated by a future form of online advertising given current trends and concerns. Specifically, the model of [Feldman and Gonen (2016)] introduces user information markets through information brokers into the online advertising ecosystem, and thus, overcomes privacy concerns and gives users control over which of their data get shared in the online advertising market.