Testing Neoclassical Competitive Theory in Multilateral Decentralized Markets

Walrasian tâtonnement has been a fundamental assumption in economics ever since Walras’ general equilibrium theory was introduced in 1874. Nearly a century after its introduction, Vernon Smith relaxed the Walrasian tâtonnement assumption by showing that neoclassical competitive market theory explains the equilibrating forces in “double‐auction” markets. I make a next step in this evolution by exploring the predictive power of neoclassical theory in decentralized naturally occurring markets. Using data gathered from two distinct markets—the sports card and collector pin markets—I find a tendency for exchange prices to approach the neoclassical competitive model prediction after a few market periods.