What is a Negative Volume Index (NVI)?
A negative volume index (NVI) identifies days in which trading volume of a particular security is substantially lower than other days.
How Does a Negative Volume Index (NVI) Work?
Mathematically, the NVI compares the day's volatility to its moving average:
If V < V-1, then NVI = NVI-1 + ((Px - Px-1) / Px-1)
If V > V-1, then NVI = NVI-1
where V = today's trading volume, V-1 = yesterday's trading volume, NVI-1 = yesterday's NVI, Px = today's closing price, and Px-1 = yesterday's closing price.
Intuitively, the formula states that if the volume of a particular security today is less than it was yesterday, then the NVI is equal to yesterday's NVI plus the percentage change in the stock's closing price. If today's volume is higher than yesterday's volume, the NVI stays the same.
Why Does a Negative Volume Index (NVI) Matter?
The key assumption behind the NVI is that changes in volume and changes in price are correlated. In particular, many traders believe that unsophisticated investors rush the market and are thus the primary force behind high-volume days. Thus, the general objective of the NVI is to highlight low-volume days on which more sophisticated investors can buy and sell without "being noticed."
Personalized Financial Plans for an Uncertain Market
In today’s uncertain market, investors are looking for answers to help them grow and protect their savings. So we partnered with Vanguard Advisers -- one of the most trusted names in finance -- to offer you a financial plan built to withstand a variety of market and economic conditions. A Vanguard advisor will craft your customized plan and then manage your savings, giving you more confidence to help you meet your goals. Click here to get started.
