Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for identifying an auction element comprising one or more placement groups, ranking a plurality of advertising elements that each advertising element comprises an advertiser, one or more user target areas, one or more campaigns, and one or more creative elements, submitting top-ranked advertising elements for selection in auctions for the auction element, selecting, from the submitted top-ranked advertising elements, one or more advertising elements each having at least one success event for a specified number of impressions from the auctions for the auction element, and generating delivery allocation for the creative elements of the selected advertising elements.