Designing a Strategy-Proof Spot Market Mechanism with Many Traders: Twenty-Two Steps to Walrasian Equilibrium

To prove their Walrasian equilibrium existence theorem, Arrow and Debreu (1954) devised an abstract economy that Shapley and Shubik (1977) cricitized as a market game because, especially with untrustworthy traders, it fails to determine a credible outcome away from equilibrium. All this earlier work also postulated a Walrasian auctioneer with complete information about traders’ preferences and endowments. To ensure credible outcomes, even in disequilibrium, warehousing is introduced into a multi-stage market game. To achieve Walrasian outcomes in a large economy with incomplete information, even about traders’ endowments, a strategy-proof demand revelation mechanism is considered, and then extended to include warehousing.