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1. "Asymmetric Information and Sovereign Debt: Theory Meets Mexican Data."

   Cole, Harold; Neuhann, Daniel; Ordonez, Guillermo (August 2022, Journal of political economy)

   Greg Kaplan (Ed.)

   Using bid-level data from discriminatory auctions for Mexican government bonds, we demonstrate that asymmetric information about default risk is a key friction in sovereign bond markets. We document that large bidders achieve higher bid-acceptance rates than other bidders despite paying no more for executed bids.We then propose a new model of primary markets in which investors may differ in wealth, risk aversion, market power, and information. Only asymmetric information can qualitatively account for our empirical finding, and asymmetric information about rare disasters can quantitatively match bidding and yield moments. Counterfactuals reveal substantial effects of asymmetric information on yields. 

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2. Optimal Deterministic Clock Auctions and Beyond

   Christodoulou, Giorgos; Gkatzelis, Vasilis; Schoepflin, Daniel (February 2022, 13th Innovations in Theoretical Computer Science Conference (ITCS 2022))

   We design and analyze deterministic and randomized clock auctions for single-parameter domains with downward-closed feasibility constraints, aiming to maximize the social welfare. Clock auctions have been shown to satisfy a list of compelling incentive properties making them a very practical solution for real-world applications, partly because they require very little reasoning from the participating bidders. However, the first results regarding the worst-case performance of deterministic clock auctions from a welfare maximization perspective indicated that they face obstacles even for a seemingly very simple family of instances, leading to a logarithmic inapproximability result; this inapproximability result is information-theoretic and holds even if the auction has unbounded computational power. In this paper we propose a deterministic clock auction that achieves a logarithmic approximation for any downward-closed set system, using black box access to a solver for the underlying optimization problem. This proves that our clock auction is optimal and that the aforementioned family of instances exactly captures the information limitations of deterministic clock auctions. We then move beyond deterministic auctions and design randomized clock auctions that achieve improved approximation guarantees for a generalization of this family of instances, suggesting that the earlier indications regarding the performance of clock auctions may have been overly pessimistic. 

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3. Contextual Standard Auctions with Budgets: Revenue Equivalence and Efficiency Guarantees

   https://doi.org/10.1287/mnsc.2023.4719  

   Balseiro, Santiago; Kroer, Christian; Kumar, Rachitesh (January 2023, Management Science)

   The internet advertising market is a multibillion dollar industry in which advertisers buy thousands of ad placements every day by repeatedly participating in auctions. An important and ubiquitous feature of these auctions is the presence of campaign budgets, which specify the maximum amount the advertisers are willing to pay over a specified time period. In this paper, we present a new model to study the equilibrium bidding strategies in standard auctions, a large class of auctions that includes first and second price auctions, for advertisers who satisfy budget constraints on average. Our model dispenses with the common yet unrealistic assumption that advertisers’ values are independent and instead assumes a contextual model in which advertisers determine their values using a common feature vector. We show the existence of a natural value pacing–based Bayes–Nash equilibrium under very mild assumptions. Furthermore, we prove a revenue equivalence showing that all standard auctions yield the same revenue even in the presence of budget constraints. Leveraging this equivalence, we prove price of anarchy bounds for liquid welfare and structural properties of pacing-based equilibria that hold for all standard auctions. In recent years, the internet advertising market has adopted first price auctions as the preferred paradigm for selling advertising slots. Our work, thus, takes an important step toward understanding the implications of the shift to first price auctions in internet advertising markets by studying how the choice of the selling mechanism impacts revenues, welfare, and advertisers’ bidding strategies. This paper was accepted by Itai Ashlagi, revenue management and market analytics. Supplemental Material: The online appendix is available at https://doi.org/10.1287/mnsc.2023.4719 . 

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4. Competitive Equilibrium Always Exists for Combinatorial Auctions with Graphical Pricing Schemes

   https://doi.org/10.1007/s44007-022-00038-7  

   Brandenburg, Marie-Charlotte; Haase, Christian; Tran, Ngoc Mai (December 2022, La Matematica)

   Abstract We show that a competitive equilibrium always exists in combinatorial auctions with anonymous graphical valuations and pricing, using discrete geometry. This is an intuitive and easy-to-construct class of valuations that can model both complementarity and substitutes, and to our knowledge, it is the first class besides gross substitutes that have guaranteed competitive equilibrium. We prove through counter-examples that our result is tight, and we give explicit algorithms for constructing competitive pricing vectors. We also give extensions to multi-unit combinatorial auctions (also known as product-mix auctions). Combined with theorems on graphical valuations and pricing equilibrium of Candogan, Ozdagar and Parrilo, our results indicate that quadratic pricing is a highly practical method to run combinatorial auctions. 

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5. Deterministic Budget-Feasible Clock Auctions

   https://doi.org/10.1137/1.9781611977073.114  

   Balkanski, Eric; Garimidi, Pranav; Gkatzelis, Vasilis; Schoepflin, Daniel; Tan, Xizhi (January 2022, 33rd ACM-SIAM Symposium on Discrete Algorithms (SODA22))

   We revisit the well-studied problem of budget-feasible procurement, where a buyer with a strict budget constraint seeks to acquire services from a group of strategic providers (the sellers). During the last decade, several strategyproof budget-feasible procurement auctions have been proposed, aiming to maximize the value of the buyer, while eliciting each seller’s true cost for providing their service. These solutions predominantly take the form of randomized sealed-bid auctions: they ask the sellers to report their private costs and then use randomization to determine which subset of services will be procured and how much each of the chosen providers will be paid, ensuring that the total payment does not exceed the buyer’s budget. Our main result in this paper is a novel method for designing budget-feasible auctions, leading to solutions that outperform the previously proposed auctions in multiple ways. First, our solutions take the form of descending clock auctions, and thus satisfy a list of very appealing properties, such as obvious strategyproofness, group strategyproofness, transparency, and unconditional winner privacy; this makes these auctions much more likely to be used in practice. Second, in contrast to previous results that heavily depend on randomization, our auctions are deterministic. As a result, we provide an affirmative answer to one of the main open questions in this literature, asking whether a deterministic strategyproof auction can achieve a constant approximation when the buyer’s valuation function is submodular over the set of services. In addition to this, we also provide the first deterministic budget-feasible auction that matches the approximation bound of the best-known randomized auction for the class of subadditive valuations. Finally, using our method, we improve the best-known approximation factor for monotone submodular valuations, which has been the focus of most of the prior work 

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