Rule 611 of Regulation NMS currently requires trading centers to maintain and enforce reasonably designed policies and procedures to prevent trade-throughs of protected quotations unless an enumerated exception applies. The rule is not an absolute statement that every better displayed price must always be reached: Rule 611 contains defined scope and exceptions. The SEC proposed rescinding Rule 611 in June 2026, but the proposal is not a final repeal as of this review.
ReviewedEvidence3 sourcesSectionPhrases & Idioms
Quick answer
Rule 611 of Regulation NMS currently requires trading centers to maintain and enforce reasonably designed policies and procedures to prevent trade-throughs of protected quotations unless an enumerated exception applies.
Key details
Canonical FormOrder Protection Rule
Core MeaningRule 611 of Regulation NMS currently requires trading centers to maintain and enforce reasonably designed policies and procedures to prevent trade-throughs of protected quotations unless an enumerated exception applies.
Further guidance
History Boundary
Current regulatory/market-structure meaning is published without claiming an exact inventor, coinage date, or absolute first use.
Meaning
Rule 611 of Regulation NMS currently requires trading centers to maintain and enforce reasonably designed policies and procedures to prevent trade-throughs of protected quotations unless an enumerated exception applies.
Usage Boundary
The rule is not an absolute statement that every better displayed price must always be reached: Rule 611 contains defined scope and exceptions. The SEC proposed rescinding Rule 611 in June 2026, but the proposal is not a final repeal as of this review.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
Categorized by Order Size is a current Regulation NMS defined term. This guide keeps the reporting classification tied to the enumerated rule buckets rather than informal size labels.
Categorized by Order Type is a current Regulation NMS defined term. This guide preserves the rule’s specific order-type classification rather than replacing it with a simplified trading glossary.
Under current U.S. Regulation NMS, a “covered order” is a rule-defined class of market and limit orders received by a market center, broker, or dealer under the timing and quotation conditions in § 242.600, subject to stated exclusions. The definition contains timing, NBBO, execution, and special-handling conditions and exclusions; do not reduce “covered order” to every market or limit order.
Under current U.S. Regulation NMS, a “customer limit order” is an order to buy or sell an NMS stock at a specified price that is not for a broker or dealer account, and it includes an order transmitted by a broker or dealer on behalf of a customer. Keep this definition tied to NMS stock, a specified price, and the rule’s express inclusion of orders transmitted by a broker or dealer on behalf of a customer.
Under current U.S. Regulation NMS, a “customer order” is an order to buy or sell an NMS security that is not for a broker or dealer account, subject to the rule’s stated market-value exclusions. Use the § 242.600 definition for rule-scoped analysis. The definition excludes orders meeting the stated market-value thresholds, so it should not be reduced to every order placed for a non-broker/dealer account.
Under current U.S. Regulation NMS, a “directed order” is an order from a customer who specifically instructed the broker or dealer to route it to a particular venue for execution. Use the § 242.600 definition for rule-scoped analysis; the customer’s specific routing instruction is the defining feature, so do not broaden the term to every order a broker routes to a venue.
Executable Stop Marketable Limit Order is a current Regulation NMS defined term. This guide preserves the rule-specific conditions instead of replacing them with informal trading shorthand.
Executable Stop Non-Marketable Limit Order is a current Regulation NMS defined term. This guide preserves the rule-specific conditions instead of replacing them with informal trading shorthand.
