A locked market occurs when the best bid to buy equals the best offer to sell. A locked market is not the same as a crossed market: equality of the best bid and offer is locked, while a bid above the best offer is crossed. Regulatory treatment also depends on the specific rule and benchmark context.
ReviewedEvidence1 sourceSectionPhrases & Idioms
Quick answer
A locked market occurs when the best bid to buy equals the best offer to sell.
Key details
Canonical Formlocked market
Core MeaningA locked market occurs when the best bid to buy equals the best offer to sell.
Further guidance
History Boundary
Current authoritative market-structure meaning is published without claiming an exact inventor, coinage date, or absolute first use.
Meaning
A locked market occurs when the best bid to buy equals the best offer to sell.
Usage Boundary
A locked market is not the same as a crossed market: equality of the best bid and offer is locked, while a bid above the best offer is crossed. Regulatory treatment also depends on the specific rule and benchmark context.
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.
A “bear market” is a period in which financial-market investments are generally falling in value. The dictionary definition does not require one universal percentage threshold, so do not make a fixed numeric cutoff part of the core meaning.
Consolidated Market Data is a current Regulation NMS defined term for enumerated data consolidated across national securities exchanges and associations.
Consolidated Market Data Product is a current Regulation NMS defined term. This guide preserves the specific U.S. securities-rule scope instead of substituting an ordinary-language meaning.
A crossed market occurs when the best bid to buy is higher than the best offer to sell. A crossed market is distinct from a locked market and can make an NBBO unreliable for some execution-quality calculations; do not use the terms interchangeably.
A national market system plan approved by the Securities and Exchange Commission, temporarily or permanently, pursuant to § 242.608. Keep the approval and § 242.608 scope in the definition; this is not a generic label for any market-system operating plan.
Under current U.S. Regulation NMS, an “exchange market maker” is a member of a national securities exchange registered as a specialist or market maker under that exchange’s rules. Keep this definition tied to the Regulation NMS rule text; it does not define every market-making role outside that regulatory context.
Under current U.S. Regulation NMS, “market center” means any exchange market maker, OTC market maker, alternative trading system, national securities exchange, or national securities association. This is the enumerated § 242.600 definition and should not be broadened to every venue, broker, or securities-market participant.
