Study guide
When a customer order arrives, a web of duties attaches instantly: the duty to seek the best market, to charge fair prices, to keep the firm's own trading out of the customer's way, and to respect the display and pricing rules of Regulation NMS. This chapter, still within the heavily weighted Trading Activities function, covers the customer-facing obligations that regulators enforce most aggressively.
Best Execution and Interpositioning: FINRA Rule 5310
FINRA Rule 5310 requires a member handling a customer order to use reasonable diligence to ascertain the best market for the security and to buy or sell in that market so the resulting price is as favorable as possible under prevailing conditions. Reasonable diligence is judged by factors the exam loves to list: the character of the market for the security, including price, volatility, and relative liquidity; the size and type of the transaction; the number of markets checked; the accessibility of quotations; and the terms and conditions of the order as communicated by the customer. Best execution applies whether the firm executes the order itself or routes it elsewhere, and it applies to orders received from other broker-dealers as well as from the firm's own customers. A firm that does not conduct an order-by-order review of execution quality must instead perform a regular and rigorous review, comparing the quality its orders receive against what competing markets offer and making changes when the comparison is unfavorable. Payment for order flow and internalization arrangements never excuse inferior executions. The rule also targets interpositioning: a member may not insert a third party between itself and the best market unless doing so improves the price for the customer. Imagine Halloway Capital routes a customer buy order through an affiliated dealer, Kestrel Trading, which buys at 20.00 and resells to Halloway at 20.05 before the customer is filled at 20.07. Unless that detour somehow produced a better outcome than going directly to the best market, Halloway has violated 5310 by letting a middleman skim the customer's price.
Fair Prices, Commissions, and Net Transactions: Rules 2121 and 2124
FINRA Rule 2121 requires that markups, markdowns, and commissions be fair and reasonable. The familiar 5 percent policy is a guideline, not a rule of law: 5 percent is not automatically fair, and more than 5 percent is not automatically unfair. Fairness turns on the type of security, since equities generally bear higher percentages than bonds; the availability of the security; the price, because percentage charges reasonably run higher on low-priced securities; the amount of money involved; whether the charge was disclosed; the member's pattern of markups; and the nature of the member's business. A markup is normally measured from the prevailing market price, and for a dealer that dominates or controls the market in a security, or trades risklessly, the firm's own contemporaneous cost becomes the benchmark, since its quotes cannot be trusted as an independent measure. A riskless principal transaction, where the dealer buys only after receiving the customer order it will fill, is charged and disclosed like an agency trade in substance. Rule 2124 governs net transactions, in which a firm receives a customer order, executes for its own account at one price, and fills the customer at a different price, keeping the spread as compensation rather than charging a stated commission or markup. Net trading with a customer requires consent. In most cases an institutional customer may consent through a negative consent letter that discloses the practice, through oral disclosure and consent at the time of each order, or through a standing written agreement; a retail customer must give affirmative written consent on an order-by-order basis before execution. Records of the consent must be preserved.
Extended-Hours Risk Disclosure and Adjusting Open Orders: Rules 2265, 5330, and 5350
Before a firm permits a customer to trade in extended hours, FINRA Rule 2265 requires delivery of a risk disclosure describing what makes pre-market and after-hours sessions different: lower liquidity and wider spreads, higher volatility, greater price uncertainty relative to the official close, unlinked markets where the price on one venue may not reflect prices elsewhere, the outsized effect of news announcements released outside regular hours, and, for some sessions, wider quoted spreads. FINRA Rule 5330 handles what happens to open orders held by a firm when a security goes ex-dividend or splits. On the ex-date, open buy limit orders and open sell stop orders, the order types resting below the market, are reduced by the dollar amount of a cash dividend, because the stock is expected to open lower by roughly that amount; open sell limit and buy stop orders, which rest above the market, are not adjusted. A customer can avoid the cash dividend adjustment by marking the order do not reduce, or DNR. For stock splits and stock dividends, both price and share quantity are adjusted proportionally so the total economics are preserved: a buy limit for 100 shares at 60 becomes 200 shares at 30 after a two-for-one split. In a reverse split, open orders are generally cancelled outright. Rule 5350 permits members to accept stop and stop-limit orders and specifies the default trigger: a stop is elected by a transaction at or through the stop price. A firm may offer alternative triggers, such as a quotation-based trigger, only if the customer receives clear disclosure of how the order will be handled.
Trading Ahead of Customer Orders: FINRA Rule 5320
FINRA Rule 5320, descended from the Manning decision, prohibits a member that holds an unexecuted customer order from trading that security for its own account at a price that would satisfy the customer's order, unless the firm immediately thereafter executes the customer order up to the size of its own trade at the same or a better price. If Brightline holds Ana's limit order to buy 500 shares at 25.10 and the firm buys 500 shares for its own book at 25.05, it must immediately fill Ana at 25.05 or better. The rule has calibrated exceptions. Under the no-knowledge exception, a proprietary desk walled off from the desk holding customer orders by effective information barriers may trade without reference to those orders, with the barriers documented. Large orders and institutional accounts can opt out: for orders of 10,000 shares or more that are also worth at least 100,000 dollars, and for institutional accounts as defined by FINRA, the firm may trade alongside or ahead if it has given clear written disclosure of its practices and the customer has been offered a meaningful way to opt in to full 5320 protection. Odd-lot orders and bona fide error corrections are also excepted, and riskless principal handling satisfies the rule when properly documented and reported. Finally, the minimum price improvement standards prevent a token step-ahead: a firm that wants to trade for its own account at a price better than a held customer limit order must improve by at least a minimum increment, one cent for stocks priced 1 dollar or more, with smaller prescribed increments below 1 dollar.
Regulation NMS: Order Protection, Limit Order Display, and Sub-Penny Pricing
Three Regulation NMS rules anchor this chapter. Rule 611, the order protection rule, requires trading centers to maintain policies reasonably designed to prevent trade-throughs, meaning executions at prices inferior to a protected quotation displayed by another venue. A protected quotation is an automated, immediately accessible top-of-book bid or offer of a national securities exchange or the ADF during regular hours. The exceptions matter as much as the rule: an intermarket sweep order, or ISO, lets a trading center execute immediately at its own price so long as the sender simultaneously routes orders to execute against all better-priced protected quotations; other exceptions cover benchmark trades such as VWAP executions, qualified contingent trades, flickering quotations that changed within the preceding second, single-priced opening and closing crosses, and self-help, which a venue may declare against another venue that fails to respond to orders within one second. Rule 604 requires market makers and specialists to display customer limit orders that improve their quoted price, or that add meaningful size at a quote already at the national best, within 30 seconds of receipt. Exceptions include block-size orders of at least 10,000 shares or 200,000 dollars, all-or-none orders, odd lots, orders the customer asked not to display, orders executed on receipt, and orders promptly routed to another displaying venue. Rule 612 bans accepting or displaying orders and quotations in sub-penny increments for NMS stocks priced at 1 dollar or more, and in increments finer than one hundredth of a cent below 1 dollar; executions at sub-penny prices, such as midpoint fills, remain permissible. Note that SEC amendments adopted in 2024 would introduce a half-penny quoting increment for certain tick-constrained stocks; the SEC has delayed compliance until November 2026, so confirm the current status before exam day.
Key terms
- Reasonable diligence
- — The best execution standard of Rule 5310, judged by the character of the market, the size and type of transaction, the number of markets checked, the accessibility of quotations, and the terms of the order.
- Regular and rigorous review
- — The periodic execution-quality comparison a firm must perform against competing markets when it does not review executions order by order.
- Interpositioning
- — Inserting a third party between the member and the best market in a customer transaction, prohibited unless it improves the customer's price.
- 5 percent policy
- — FINRA's markup guideline under Rule 2121: a benchmark, not a safe harbor, with fairness judged by security type, availability, price, amount, disclosure, pattern, and the firm's business.
- Net transaction
- — A principal trade in which the firm fills a customer at a price different from its own offsetting execution, keeping the spread; retail customers must give affirmative written consent order by order under Rule 2124, while institutions have more flexible consent options.
- Extended-hours risk disclosure
- — The Rule 2265 document covering lower liquidity, higher volatility, price uncertainty, unlinked markets, news effects, and wider spreads, required before a customer trades outside regular hours.
- Do not reduce (DNR)
- — A customer instruction preventing the automatic downward adjustment of an open buy limit or sell stop order by a cash dividend on the ex-date under Rule 5330.
- Manning obligation
- — The Rule 5320 duty: a firm trading for its own account at a price that would satisfy a held customer order must immediately execute that customer order, up to the size it traded, at the same or a better price.
- No-knowledge exception
- — The 5320 exception allowing a proprietary desk separated by documented information barriers to trade without reference to customer orders held on another desk.
- Protected quotation
- — An automated, immediately accessible best bid or offer displayed by an exchange or the ADF during regular hours, which Rule 611 shields from trade-throughs.
- Intermarket sweep order (ISO)
- — An order permitting immediate execution at one venue because the sender simultaneously routes orders against all better-priced protected quotations elsewhere.
- Sub-penny rule (Rule 612)
- — The ban on accepting or displaying quotations in increments under one cent for NMS stocks priced 1 dollar or more, and under one hundredth of a cent below 1 dollar; sub-penny executions such as midpoint fills remain allowed.
Exam tips
- Best execution questions often hinge on the diligence factors: character of the market, size and type of order, number of markets checked, accessibility of quotes, and the order's terms; payment for order flow never excuses a worse price.
- For Rule 5330 adjustments, remember which orders live below the market: buy limits and sell stops are reduced on the ex-date for cash dividends, sell limits and buy stops are not, DNR opts out, splits adjust both price and quantity, and reverse splits generally cancel open orders.
- The 5320 large-order opt-out has two numeric prongs that must both be met: 10,000 shares or more and at least 100,000 dollars in value, and it also requires disclosure plus a genuine chance for the customer to choose full protection.
- Know the Rule 611 exceptions by name, especially the ISO, benchmark and VWAP trades, qualified contingent trades, and the one-second flickering quote and self-help provisions; expect a question that describes one without naming it.
- Rule 604's display clock is 30 seconds, and its block-size exception is 10,000 shares or 200,000 dollars; do not confuse those thresholds with the similar-sounding 5320 opt-out, which requires both prongs together.