Retail Execution Quality
Retail execution quality refers to the overall standard of trade execution received by individual investors when their stock orders are filled, encompassing metrics such as effective spread, price improvement, fill rate, speed of execution, and the extent to which realized execution prices compare favorably to the national best bid and offer at the time of order submission.
For decades, evaluating the quality of retail order execution was difficult because the data was sparse and the metrics were not standardized. The introduction of SEC Rule 605 and Rule 606 under Regulation NMS created a framework for systematic, publicly reported measurement. Rule 605 requires market centers to publish monthly execution quality statistics covering effective spreads, price improvement, and fill rates by order type and size. Rule 606 requires brokers to disclose the routing destinations for their customers' orders.
The most fundamental retail execution quality metric is the effective spread: the difference between the price at which an order is filled and the midpoint of the bid-ask spread at the time the order was received, expressed as a percentage of the midpoint. An effective spread smaller than the quoted spread indicates price improvement, meaning the customer received a fill at a price better than the displayed best bid or offer. Wholesale market makers executing retail PFOF orders routinely report price improvement rates well above 90 percent for eligible orders, and they cite these statistics as evidence that off-exchange internalization benefits retail customers.
Critics have raised methodological concerns about these statistics. They argue that the relevant comparison is not merely whether the customer received a price better than the NBBO — a low bar given that the NBBO may itself reflect a wide spread — but whether the fill was as good as what would have been available through competitive displayed market mechanisms. Some academic studies have found that when institutional and retail orders are compared on equivalent terms, the realized execution quality for retail orders routed through PFOF arrangements is measurably inferior to what displayed limit order markets deliver for comparable order sizes.
The SEC proposed significant changes to Rule 605 and Rule 606 disclosures in its 2022 equity market structure package, seeking more granular and standardized reporting that would enable rigorous cross-venue comparison of retail execution quality. The proposals included expanding the range of order types and sizes reported, requiring disclosure of effective spreads at narrower price-improvement intervals, and mandating that brokers report execution quality statistics aggregated by routing venue. These changes were intended to give investors and researchers better tools to hold brokers and market makers accountable for the quality of retail order execution.