Negative Volume Index (NVI) is a forex technical indicator often used in technical analysis. Negative Volume Index (NVI) was developed by Norman Fosback in 1976. NVI is an indicator that focuses on the time when trading volume declined compared with previous days.

This method assumes that many investors who have enough information to play in the stock market when trading volumes are down (low). Conversely, when trading volumes are rising (high), the stock market usually dominated by the average investor.

Because NVI using the assumption that many investors have adequate information were playing in the stock market when trading volume is low (down) and vice versa, then the days where volume fell to very important. NVI can be used to indicate what is being done by investors who experienced it.

NVI is a very useful indicator when the market is in a bullish state. According to Norman Fosback, there is a 95% probability that the market is in a bullish if NVI is above a value of 1 year of his moving-average. The probability is decreased to be 50% if the NVI is below a value of 1 year of his moving-average.