We study whether Amazon engages in self-preferencing on its marketplace by favoring its
own brands (e.g., Amazon Basics) in search. To address this question, we collect new microlevel consumer search data using a custom browser extension installed by a panel of study
participants. Using this methodology, we observe search positions, search behavior, and
product characteristics. We find that Amazon branded products are indeed ranked higher
than observably similar products in consumer search results. The prominence given to Amazon brands is 30% to 60% of the prominence granted to sponsored products.