Trading System

NSE operates on the 'National Exchange for Automated Trading' (NEAT) system, a fully automated screen based trading system, which adopts the principle of an order driven market. NSE consciously opted in favour of an order driven system as opposed to a quote driven system. This has helped reduce jobbing spreads not only on NSE but in other exchanges as well, thus reducing transaction costs.

Features of trading system on ITP platform:

Normal Market

All orders which are of regular lot size or multiples thereof are traded in the Normal Market. Normal market consists of various book types wherein orders are segregated as Regular lot orders and Stop Loss orders depending on their order attributes.

Order Book

Orders are first numbered and time-stamped on receipt and then immediately processed for potential match. Every order has a distinctive order number and a unique time stamp on it. If a match is not found, then the orders are stored in different 'books'. Orders are stored in price-time priority in various books in the following sequence:

  1. Best Price
  2. Within Price, by time priority

Book Type:

Regular Lot Book

The Regular Lot Book contains all regular lot orders that have none of the following attributes attached to them.

  1. All or None (AON)
  2. Minimum Fill (MF)
  3. Stop Loss (SL)

Stop-Loss Book

Stop Loss orders are stored in this book till the trigger price specified in the order is reached or surpassed. When the trigger price is reached or surpassed, the order is released in the Regular lot book. The stop loss condition is met under the following circumstances:

Sell order - A sell order in the Stop Loss book gets triggered when the last traded price in the normal market reaches or falls below the trigger price of the order.

Buy order - A buy order in the Stop Loss book gets triggered when the last traded price in the normal market reaches or exceeds the trigger price of the order.

Order Matching Rules

The best buy order is matched with the best sell order. An order may match partially with another order resulting in multiple trades. For order matching, the best buy order is the one with the highest price and the best sell order is the one with the lowest price. This is because the system views all buy orders available from the point of view of a seller and all sell orders from the point of view of the buyers in the market. So, of all buy orders available in the market at any point of time, a seller would obviously like to sell at the highest possible buy price that is offered. Hence, the best buy order is the order with the highest price and the best sell order is the order with the lowest price.

Members can proactively enter orders in the system, which will be displayed in the system till the full quantity is matched by one or more of counter-orders and result into trade(s) or is cancelled by the member. Alternatively, members may be reactive and put in orders that match with existing orders in the system. Orders lying unmatched in the system are 'passive' orders and orders that come in to match the existing orders are called 'active' orders. Orders are always matched at the passive order price. This ensures that the earlier orders get priority over the orders that come in later.

Order Conditions

A Trading Member can enter various types of orders depending upon his/her requirements. These conditions are broadly classified into categories: time related conditions & price-related conditions:

Time Conditions

  • DAY - A Day order, as the name suggests, is an order which is valid for the day on which it is entered. If the order is not matched during the day, the order gets cancelled automatically at the end of the trading day.
  • IOC - n Immediate or Cancel (IOC) order allows a Trading Member to buy or sell a security as soon as the order is released into the market, failing which the order will be removed from the market. Partial match is possible for the order, and the unmatched portion of the order is cancelled immediately.

Price Conditions

  • Limit Price/Order – An order that allows the price to be specified while entering the order into the system.
  • Market Price/Order – An order to buy or sell securities at the best price obtainable at the time of entering the order.
  • Stop Loss (SL) Price/Order – The one that allows the Trading Member to place an order which gets activated only when the market price of the relevant security reaches or crosses a threshold price. Until then the order does not enter the market.
    A sell order in the Stop Loss book gets triggered when the last traded price in the normal market reaches or falls below the trigger price of the order. A buy order in the Stop Loss book gets triggered when the last traded price in the normal market reaches or exceeds the trigger price of the order.