will give a presentation on:
This paper analyzes the impact of intermediary concentration on the allocation of revenues in online platforms. We study sponsored search documenting how advertisers increasingly bid through a handful of specialized intermediaries. This enhances automated bidding and data pooling, but lessens competition whenever the intermediary represents competing advertisers. Using data on nearly 40 million Google keyword-auctions, we first apply machine learning algorithms to cluster keywords into thematic groups serving as relevant markets. Using an instrumental variable strategy, we estimate a decline in the platform’s revenues of approximately 11 percent due to the average rise in concentration associated with intermediary M&A activity.