Like a lot of regulations, Reg NMS was well-meaning and sensible. If everyone on Wall Street abided by the rule’s spirit, the rule would have established a new fairness in the U.S. stock market. The rule, however, contained a loophole: It failed to specify the speed of the SIP. To gather and organize the stock prices from all the exchanges took milliseconds. It took milliseconds more to disseminate those calculations. The technology used to perform these calculations was old and slow, and the exchanges apparently had little interest in improving it. There was no rule against high-frequency
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