Shared Agents and Competition in Laboratory English Auctions

At livestock auctions, the same purchasing agent can represent more than one processor. Repeated multiple-unit English auctions are created in a laboratory to measure the impact of shared agents on trade prices under alternative treatments with six, and as few as two, agents representing six principals. Treatments are constructed in which the agents either know or do not know quantity for sale, and in which there are progressively fewer agents bidding. Knowledge of quantity for sale can be anticompetitive. Evolution toward increased market concentration leads to consistent anticompetitive pricing, resulting in prices significantly lower than the predicted competitive equilibrium prices.