This is how it works: The likelihood of executing a trade at the best price depends on the length of the queue to buy or sell and the incentives to trade. Longer queues lead to longer delays to execute a trade. Delays typically lead to worse outcomes. Quite simply, it makes no sense to wait on a longer line to receive a worse execution.

And yet, brokers choose longer queues hundreds of thousands, if not millions, of times a day. Publicly available trade and quote data show that the queues to buy or sell stock are considerably longer on exchanges that offer kickbacks. Even though the queues decrease the likelihood of getting a trade completed and impair the price performance after the trade is executed, brokers still direct trades to these places because of the kickbacks they receive.

One exchange, the IEX, refuses to pay rebates. Created by Brad Katsuyama (whose odyssey to defy the ethos of Wall Street was told in Michael Lewis’s “Flash Boys”), IEX has a speed bump that prevents high-frequency traders from front-running ordinary investors. (Yale University, where we work, has a de minimis exposure to IEX through an investment by one of the university’s external managers.)

Since opening on Aug. 19, 2016, IEX has delivered on its promise of better execution. Consider data on effective spread, which measures an exchange’s ability to provide trade executions at attractive prices. A lower effective spread is good for investors, since the gap between what buyers pay and what sellers receive is smaller.