The total number of securities (e.g., shares or contracts) that have been traded (purchased and sold) in a specific period of time (e.g., day, week, month, etc.) or during the trading day. In this sense, market volume is an indicator of the total amount of securities that change hands during a specific time window (market-specific indicator of volume).

It may also imply the total number of a specific security (e.g., XYZ stock) that has been traded within a defined timeframe (firm- or stock-specific indicator of volume).

Trading volume is also known as a market volume.