Targeting Information in Ad Auction Mechanisms
Srinivas Tunuguntla, Carl F. Mela, Jason Pratt
TL;DR
The paper tackles how publishers should monetize impression opportunities when targeting information is privately observed, introducing IBPA, a mechanism that combines information bundling with marginal-revenue allocation across multidimensional advertiser valuations. By treating inventory type as private and soliciting multidimensional bids, IBPA implements second-degree price discrimination within each advertiser and a Myerson-style marginal-revenue allocation across advertisers and slots, ensuring incentive compatibility and non-negative advertiser payoffs. The authors prove that IBPA revenue is monotone in information granularity and decreasing in disclosure, and that IBPA dominates GSP under all information regimes. They also provide computationally efficient approximations and validate the approach with auction data from a large retailer, reporting substantial gains in publisher revenue and overall welfare. The work has practical implications for ad auctions in both display and search, offering a scalable, principled alternative to current practices and inviting further exploration of transparency and equilibrium effects in multi-publisher ecosystems.
Abstract
Digital advertising platforms and publishers sell ad inventory that conveys targeting information, such as demographic, contextual, or behavioral audience segments, to advertisers. While revealing this information improves ad relevance, it can reduce competition and lower auction revenues. To resolve this trade-off, this paper develops a general auction mechanism -- the Information-Bundling Position Auction (IBPA) mechanism -- that leverages the targeting information to maximize publisher revenue across both search and display advertising environments. The proposed mechanism treats the ad inventory type as the publisher's private information and allocates impressions by comparing advertisers' marginal revenues. We show that IBPA resolves the trade-off between targeting precision and market thickness: publisher revenue is increasing in information granularity and decreasing in disclosure granularity. Moreover, IBPA dominates the generalized second-price (GSP) auction for any distribution of advertiser valuations and under any information or disclosure regime. We also characterize computationally efficient approximations that preserve these guarantees. Using auction-level data from a large retail media platform, we estimate advertiser valuation distributions and simulate counterfactual outcomes. Relative to GSP, IBPA increases publisher revenue by 68%, allocation rate by 19pp, advertiser welfare by 29%, and total welfare by 54%.
