We analyze a large-scale randomized field experiment in which a search engine varied the prominence of search ads for 3.3 million US users: one group of users saw the status quo, while the other saw a lower level of advertising (with prominence of search ads decreased). Revealed preference data...

This paper studies a model of search engine competition with endogenous obfuscation. Platforms may differ in the quality of their search algorithms. I study the impact of this heterogeneity in consumer surplus, seller profits and platform revenue. I show that the dominant platform will typically...