Time and Sales
A real-time data feed — also called the tape — that shows every executed trade for a security in chronological order, displaying the timestamp, price, volume, and exchange for each transaction as it occurs.
The time and sales window, colloquially known as the tape, is one of the oldest and most fundamental tools in active trading. In the era before electronic markets, actual ticker tape machines printed trade information in a continuous paper strip, and skilled tape readers developed the ability to infer the balance of buying and selling pressure from the pattern of prices and volumes scrolling by. Modern electronic time and sales is functionally identical, merely displayed on a screen.
Each line in the time and sales shows: the time of the trade (typically to milliseconds), the price at which the trade was executed, the number of shares or contracts traded, and in multi-venue markets, the exchange on which the trade occurred. Some platforms also show whether the trade was executed at the bid, at the ask, or between the two, which is used to infer direction — a trade at the ask is typically classified as buyer-initiated, while a trade at the bid is seller-initiated. This classification is the basis of the tick rule and the Lee-Ready algorithm used in academic microstructure research.
In Indian markets, NSE publishes a real-time trade feed through its market data dissemination system. Brokers incorporate this feed into their trading platforms, and most active trading terminals display a time and sales window alongside the order book (Level 2) view. Charting platforms from NSE-connected data vendors also provide access to this feed.
Active traders use time and sales in several ways. Large trades executing at the ask in rapid succession can signal aggressive institutional buying. A series of trades at the bid following a period of upward price movement can suggest distribution. Sudden acceleration in the pace of transactions — more prints per second than usual — often precedes or accompanies significant price moves. These observations form the basis of tape reading, a skill-intensive practice that some experienced proprietary traders consider more reliable than pattern-based technical analysis.
The time and sales feed is also essential for post-trade analysis. Reconstructing exactly how a large order was filled — at what prices, in what sequence, and against what counterparty sizes — requires access to the full time and sales record for the relevant period. This reconstruction is a key input to transaction cost analysis performed by institutional investors and their brokers.
High-frequency traders consume the time and sales feed as raw material for predictive models. The distribution of trade sizes, the ratio of buyer-initiated to seller-initiated volume, and the clustering of trades in time all carry information about short-term price direction that sophisticated models attempt to extract.