Social media are becoming increasingly important in our society and change the way people communicate, how they acquire information, and how they form beliefs. Experts are concerned that the rise of social media may make interaction and information exchange among like-minded individuals more...

We consider an ad network's problem of allocating the auction for each individual impression to an optimal subset of advertisers, with the goal of revenue maximization. This is a variant of bipartite matching, except that advertisers may strategize by choosing their bidding profiles and their...

We study the implications of delegating bids to a bidding agency for the revenues and efficiency of the Generalized Second-Price auction, the standard sales mechanism for allocating online ad space. The agency maximizes both its own profits and the advertisers' surplus and implements collusive...