AGV mechanism balances the budget with minimum total transfer variance
证明广义AGV机制在等价于期望预算平衡的初始机制的所有事后预算平衡机制中，唯一地最小化总转移方差，并刻画了最小化收益波动的最优机制。
Two mechanisms are equivalent if they share the same allocation rules and interim transfer rules, carrying incentive properties from one mechanism to the other. I prove the generalized d’Aspremont-Gérard-Varet (AGV) mechanism achieves minimal liquidity risk. It uniquely minimizes total transfer variance among all ex post budget-balanced mechanisms equivalent to an initial mechanism that balances the budget in expectation. Motivated by the contrast between ex ante and ex post fairness, I characterize the optimal mechanism minimizing payoff volatility. Finally, I show that in single-item auctions, a first-price auction with the optimal reserve price jointly maximizes expected revenue and minimizes revenue variance.