One of the things that gets some of the anti-HFT types going is that it&#x27;s possible to subscribe to direct exchange data feeds.<p>All exchanges are obliged to contribute to the SIP, which offers a market-wide view of quotes (prices) and historical trades.  However, because the SIP must aggregate data feeds from all exchanges and then republish this information, it&#x27;s possible to &quot;predict the future&quot; if you subscribe to the direct exchanges feeds (which are more-or-less what they send to the SIP) and avoid the added latency of a hop via the SIP&#x27;s aggregator and redistribution.<p>These direct exchange feeds are expensive, and getting more so (ie. NYSE UltraBook is $11,000&#x2F;month for the data, plus port fees, plus connectivity).  The argument is that this segments the customers such that unfair advantage is available to those who can afford to subscribe to the direct feeds.<p>More recently (last two? years) it&#x27;s been possible to get a microwave transmission of the data, rather than fiber, which is both lower-latency and more expensive again.