Definition of National Market System
Refers to over-the-counter trading. System of trading OTC stocks under the sponsorship of the NASD. Must meet certain criteria for size, profitability and trading activity. More comprehensive information is available for NMS stocks than for non-NMS stocks traded OTC (high, low, and last-sale prices, cumulative volume figures, and bid and ask quotations throughout the day). This is due to the fact that market makers must report the actual price and number of shares in each transaction within 90 seconds verses nonreal-time reporting for non-NMS stocks (thus, last sales prices and minute-to-minute volume updates are not possible).