Does Information Aggregation Depend on Market Structure? Market Makers vs. Double Auction

In this study, we experimentally investigate to what extent market efficiency depends on market micro structure by comparing the double auction system with different market maker systems. We also elicit traders' beliefs about the true value of the asset. Our results show that double auction markets aggregate information to some degree and that market maker systems do a job at least as good as double auctions. The type of market maker system influences the results: systems with few or no informed market makers do best in aggregating the information. The same pattern is present in the belief data