The best price obligation is related to the concept of trade-throughs – trades that do not take place at the best price available are seen to have “traded through” that best price.10 Trade-throughs occur when an order posted to one marketplace is preferentially matched to an inferior-priced order on the same marketplace rather than being matched to an order on another marketplace that displays the best price available. To avoid trade-throughs and ensure that they are complying with their best execution obligations, brokers must generally be able to access all marketplaces that trade a security in an efficient and timely manner. Many ATSs enable dealers to comply with their best execution and best price obligations by using smart order routers (SORs) that automatically send orders to the marketplace offering the best available price.11 In Canada, marketplaces are now required to establish policies and procedures reasonably designed to prevent trade-throughs, subject to certain prescribed exceptions (which was historically a dealer rather than marketplace obligation).12 Dealers are also subject to best execution obligations under both the securities rules and the Universal Market Integrity Rules (UMIR).13
While ATSs may present more challenges for regulators, they are a capital market reality and will likely continue to grow and innovate. As discussed in the next section, Canadian securities regulators have attempted to create a customized regulatory framework under the ATS Rules to address the reality of multiple marketplaces and continue to examine these and other issues raised by ATS proliferation.