Stocks that have experienced large volatility Today on Nov. 20, 2025

What Are Bollinger Bands Indicator?

Bollinger Bands are a technical analysis indicator developed by John Bollinger that helps traders gauge price volatility and identify potential overbought or oversold conditions. The indicator is made up of three lines plotted on a price chart. The middle band is typically a 20-period simple moving average (SMA) of the asset's price, representing its intermediate-term trend. The upper and lower bands are plotted a specified number of standard deviations (usually two) above and below the SMA. The key to understanding Bollinger Bands is their dynamic nature. The bands widen during periods of high volatility and contract during periods of low volatility, which is known as a "Bollinger Squeeze." Traders often see this contraction as a sign that a significant price move may be imminent. A common trading strategy involves using the bands to identify relative highs and lows. When the price of an asset reaches the upper band, it may be considered overbought, potentially signaling a selling opportunity. Conversely, when the price touches the lower band, it may be considered oversold, suggesting a potential buying opportunity. However, it's important to use Bollinger Bands in conjunction with other indicators for confirmation, as price can "walk the band" for extended periods during strong trends.