The transition of the advertising market from traditional media to the internet has induced a proliferation of marketing agencies specialized in bidding in the auctions that are used to sell ad space on the web. We analyze how collusive bidding can emerge from bid delegation to a common...

While a fast-growing body of research has looked at how the advent and diffusion of e-commerce has affected prices, much less work has investigated e-commerce's impact on the number and type of producers operating in an industry. This paper theoretically and empirically takes up the question of...