“…Within this literature, the closest papers to ours are, first, Olimov (2013) who argues that, in eBay auctions for used tractors, sellers use secret reserve prices to run unsuccessful auctions to learn bidders' willingness to pay and use this information in subsequent resale opportunities. 9 Second, Coey, Larsen, Sweeney, and Waisman (2021) argue that, in the context of online auctions, secret reserve prices allow the seller to observe more bids (first and second highest) and dynamically adjust her reserve price in future auctions. Our approach differs from these papers in two respects: the seller learns about the unobserved component of auction heterogeneity rather than bidder's private valuations (or distribution), and our rationale does not rely on dynamics or resale opportunities.…”