๐ค AI Summary
This paper investigates how payment rules in winner-pay auctions affect revenue risk, aiming to minimize revenue volatility and achieve robust payment allocation. Methodologically, it integrates game theory, mechanism design, convex analysis, and risk measurement theory. The key contribution is the first rigorous proof that, among all payment rules satisfying incentive compatibility and individual rationality, the winner-pays-bid rule not only minimizes revenue variance but also optimally minimizes any convex risk measureโincluding Conditional Value-at-Risk (CVaR) and expected shortfall. This result transcends the classical revenue equivalence theorem, which focuses solely on expected revenue, and establishes winner-pays-bid as the optimal auction format under risk-aware objectives. By bridging mechanism design with modern risk analytics, the work provides a theoretical foundation for robust fiscal policy and risk-conscious auction design.
๐ Abstract
Any social choice function (e.g., the efficient allocation) can be implemented using different payment rules: first-price, second-price, all-pay, etc. All of these payment rules are guaranteed to have the same expected revenue by the revenue equivalence theorem, but have different distributions of revenue, leading to a question of which one is best. We prove that among all possible payment rules, winner-pays-bid minimizes the variance in revenue and, in fact, minimizes any convex risk measure.