Day traders frequently use the trade volume index (TVI) to determine whether or not to buy into a stock. This index measures the amount of money flowing in and out of an asset.
The volume of the stock traded is a measure of how many times it is bought and sold in a given time period—commonly within a single trading day. More volume indicates higher interest in a stock—both positive or negative. Often, an increase in the volume of a stock is indicative of price movement about to transpire.