@unpublished{guan2025on, author = {Guan, Yanru and Zhang, Jiahao and Feng, Zhe and Lin, Tao}, title = {On the Coordination of Value-Maximizing Bidders}, year = {2025}, month = {November}, abstract = {While the auto-bidding literature predominantly considers independent bidding, we investigate the coordination problem among multiple auto-bidders in online advertising platforms. Two motivating scenarios are: collaborative bidding among multiple distinct bidders managed by a third-party bidding agent, and strategic bid selection for multiple ad campaigns managed by a single advertiser. We formalize this coordination problem as a theoretical model and demonstrate that a straightforward coordination mechanism, where only the highest-value bidder competes with outside bids, strictly dominates independent bidding, improving both Return-on-Spend (RoS) compliance and the total value accrued for each participating auto-bidder or ad campaign. Additionally, our simulations on synthetic and real-world datasets support the theoretical result that coordinated mechanism outperforms independent bidding. These findings highlight both the theoretical potential and the practical robustness of coordination in auto-bidding in online auctions.}, url = {http://approjects.co.za/?big=en-us/research/publication/on-the-coordination-of-value-maximizing-bidders/}, }