Is Google Search a monopoly with gatekeeping power? Regulators from the US, UK, and Europe have argued that it is based on the assumption that Google Search dominates the market for horizontal (a.k.a. “general”) web search. Google disputes this, claiming that competition extends to all vertical (a.k.a. “specialized”) search engines, and that under this market definition it does not have monopoly power. In this study we present the first analysis of Google Search’s market share under vertical segmentation of online search. We leverage observational trace data collected from a panel of US residents that includes their web browsing history and copies of the Google Search Engine Result Pages they were shown.We observe that participants’ search sessions begin at Google greater than 50% of the time in 24 out of 30 vertical market segments (which comprise almost all of our participants’ searches). Our results inform the consequential and ongoing debates about the market power of Google Search and the conceptualization of online markets in general.

The privacy laws and regulations that govern the collection, sharing, and selling of online data are changing. In the U.S., California adopted the California Consumer Privacy Act (CCPA) and the California Privacy Rights Act (CPRA), and twelve other U.S. states have adopted similar laws. Industry has responded by developing technical standards for collecting and disseminating consent information, such as the IAB CCPA Compliance Framework. While publishers are adopting this framework and the IAB is extending it to cover privacy laws in other U.S. states, recent work has observed that opt-out signals are not being honored under the framework. In this study, we take a deep dive into the IAB CCPA Compliance Framework to measure end-to-end flows of consent information and better understand why opt-out signals are not being honored. Using data crawled from top websites under different experimental conditions, we examine overall adoption of the framework, the flow of consent information from publishers to third parties and between third parties, and finally the reach of opt-out signals. Our results uncover numerous issues with the adoption and implementation of the framework that prevent users' consent choices from being honored by third parties.