In the context of futures markets, we study whether brokers allocate more favorable trades to their own accounts, and less favorable trades to their customers. We find that, within a thirty minute trading bracket, brokers on average buy at a lower price and sell at a higher price for their own...

This paper finds that marketmaking practices of dual traders are pit-specific. In the S&P 500 futures pit, the authors estimate that, because of a lower price impact, customers of dual traders pay eighteen cents less per contract on their trades, compared with customers of pure brokers....