Odd-Lot Information is a current Regulation NMS defined term. This guide preserves the rule-specific definition and boundaries instead of replacing it with informal market shorthand.
ReviewedEvidence1 sourceSectionPhrases & Idioms
Quick answer
Odd-lot information under Regulation NMS combines specified odd-lot transaction data, qualifying aggregated odd-lot orders, and the rule-defined best odd-lot buy and sell orders.
Key details
Canonical FormOdd-Lot Information
Core MeaningUnder 17 CFR § 242.600, odd-lot information includes specified odd-lot transaction data, qualifying odd-lot orders aggregated at each price level by exchange or association, and the best odd-lot order to buy and sell determined under the rule’s price, size, and time conditions.
Further guidance
History Boundary
This page reflects the current reviewed 17 CFR § 242.600 definition and should be rechecked if Regulation NMS changes.
Meaning
Under 17 CFR § 242.600, odd-lot information includes specified odd-lot transaction data, qualifying odd-lot orders aggregated at each price level by exchange or association, and the best odd-lot order to buy and sell determined under the rule’s price, size, and time conditions.
Usage Boundary
The term has multiple rule-defined components; it should not be reduced to merely any trade or order smaller than a round lot.
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.
In U.S. equity market structure, an odd lot is an amount smaller than the applicable round lot for the security. Because round-lot size can vary by NMS stock, an odd lot is defined relative to that stock’s applicable round lot; do not reduce the term to “fewer than 100 shares” in every case.
Auction Information is a current Regulation NMS term for specified, publicly disseminated exchange data generated leading up to and during securities auctions.
Consolidated Last Sale Information is a current Regulation NMS defined term. This guide preserves the specific U.S. securities-rule scope instead of substituting an ordinary-language meaning.
In current U.S. exchange usage aligned to Regulation NMS round lots, a mixed lot is an amount greater than one applicable round lot that is not an integer multiple of that round-lot size. Do not define a mixed lot by a fixed 100-share threshold: the applicable Regulation NMS round lot can vary by security, so the mixed-lot boundary moves with that assigned size.
Under current U.S. Regulation NMS, a round lot for an NMS stock is an assigned unit size that can vary with the stock’s price tier rather than always being 100 shares. Do not use “round lot” as a universal 100-share synonym: the applicable U.S. NMS size can be 100, 40, 10, or 1 share under the price-tier framework, and other markets may use different conventions.
Actionable Indication of Interest is a current federal securities-regulation defined term. This guide preserves the rule-specific definition and boundaries instead of replacing it with informal market shorthand.
Administrative Data is a current Regulation NMS defined term for specified administrative, control, and technical messages in the market-data plan framework.
Affiliate of a Subscriber is a current Regulation ATS defined term. This guide preserves the rule-specific meaning and boundary instead of replacing it with informal market shorthand.
