Volume and open interest can be used with price data to confirm a market move. The general rules are:

These rules are based on the belief that volume drives the market. If the market is moving in a certain direction, high volume and open interest confirm strong momentum in the direction the market is moving. In the opposite case, movement without much volume and open interest suggests a lack of interest, or substance to the move.

The idea is interesting but volume and open interest data can be tricky to actually use. The trader must decide whether to use the total contract amount or the individual contract amount. The total contract amount includes all the contracts traded, whereas the individual contract amount is the amount for each single contract month. Volume and open interest for a specific contract can shift dramatically in one day, because some markets change the active trading month on one day. Front and back months (near- and long-term expirations) are often related by interest rate levels. In these cases, it is usually better to use total volume and open interest figures.

Other markets change the volume and open interest amounts gradually. Some back months exhibit behavior unlike the front months, so figures for one contract month are not related to another contract month. In this case, it is better to use the individual figures for each month.