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Friday, April 24, 2026

UTP Vendor Alert #2026 - 12
Reminder : Regulation NMS Mandated Round Lot Changes

Markets Impacted:

Products Impacted:

Contact Information:

What you need to know:

  • As previously announced in UTP Vendor Alert #2025-10, on November 3, 2025, as set forth in Securities and Exchange Commission (SEC) Final Rule Notice, the SEC has adopted new definitions for “Round Lot” information under the Market Data Infrastructure (MDI) Rules to enhance the transparency for investors and other market participants of quotes and orders in NMS stocks.

  • As defined in the rule, each NMS stock will be assigned a round lot size, semiannually, based on the NMS stock’s average closing price on the primary listing exchange during a one-month Evaluation Period. The Evaluation Period are:

    • all trading days in March for the round lot assigned on the first business day in May
    • all trading days in September for the round lot assigned on the first business day of November

    During which the average closing price of an NMS stock on the primary listing exchange shall be measured by the primary listing exchange to determine the round lot for each NMS stock.

  • The UTP SIP is providing this reminder since this is the first reassignment of Round Lot designation since the rule was implemented. Any changes to round lot designations will take place on Friday May 1, 2026. For a complete list of the new designations please visit Nasdaq Round Lot Update file.