Selecting users to whom to promote an online offering

Disclosed are various embodiments for selecting users to whom to promote an online offering, such as an auction or a fixed-price item offering, based at least in part on bidding history or purchase history. A data representation of multiple items offered online by a web merchant and a purchase history associated with the items and the web merchant for multiple users are maintained. A first item is identified in response to determining that the number of users who have purchased a second item and who have also purchased the first item meets a minimum threshold. A set of users who have both purchased the second item and also purchased the first item is identified. The first item is promoted to one or more of the identified users.