Bollinger Bands: Squeezing Out the Market Noise for Better Trades

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Bollinger Bands are a powerful tool in technical analysis, offering traders insights into market volatility and potential price movements. Developed by John Bollinger in the 1980s, Bollinger Bands consist of a moving average and two standard deviation lines, which together create a band that can help traders identify overbought and oversold conditions. By effectively “squeezing out” market noise, Bollinger Bands enable traders to make more informed trading decisions. This article delves into the mechanics and applications of Bollinger Bands, providing a comprehensive guide to enhancing your trading strategies.

Bollinger Bands: Squeezing Out the Market Noise for Better Trades


Bollinger Bands are a versatile and widely used indicator in technical analysis, helping traders to identify potential buy and sell signals by analyzing market volatility. The bands consist of three lines: a simple moving average (SMA) in the middle, and an upper and lower band representing standard deviations from the SMA. By understanding and utilizing Bollinger Bands, traders can filter out market noise and make better-informed trading decisions.

Understanding Bollinger Bands

Bollinger Bands are calculated using the following components:

  • Middle Band: A simple moving average (SMA) of the closing prices, typically set at 20 periods.
  • Upper Band: The middle band plus two standard deviations of the price.
  • Lower Band: The middle band minus two standard deviations of the price.


\[ \text{Upper Band} = \text{SMA}_{20} + (2 \times \sigma) \] \[ \text{Lower Band} = \text{SMA}_{20} - (2 \times \sigma) \]

Where \( \sigma \) is the standard deviation of the closing prices.

Example Calculation

Consider the stock price of Apple Inc. (AAPL) with the following closing prices over 20 days:

\[ 150, 152, 153, 151, 149, 148, 147, 146, 145, 144, 143, 142, 141, 140, 139, 138, 137, 136, 135, 134 \]

First, calculate the 20-day SMA:

\[ \text{SMA}_{20} = \frac{\sum \text{Close}}{20} = \frac{150 + 152 + \ldots + 134}{20} = 142 \]

Next, calculate the standard deviation (\(\sigma\)):

\[ \sigma = \sqrt{\frac{\sum (Close - SMA)^2}{20}} \]

Finally, calculate the upper and lower bands:

\[ \text{Upper Band} = 142 + (2 \times \sigma) \] \[ \text{Lower Band} = 142 - (2 \times \sigma) \]

Applying Bollinger Bands in Trading

Bollinger Bands provide valuable insights into market conditions, helping traders identify potential overbought and oversold levels. When the price moves close to the upper band, it indicates overbought conditions, while a move towards the lower band suggests oversold conditions. The bands also expand and contract with volatility, providing additional context for market analysis.


If AAPL’s price moves above the upper band, traders might consider it a signal to sell or short the stock, anticipating a pullback. Conversely, if the price moves below the lower band, it might be a signal to buy, expecting a rebound.

Bollinger Band Squeeze

The Bollinger Band Squeeze is a strategy used to identify periods of low volatility that are often followed by significant price movements. When the bands contract tightly around the moving average, it indicates a squeeze, suggesting that a breakout may be imminent.


Assume AAPL’s Bollinger Bands contract tightly over several days, indicating a squeeze. Traders might watch for a breakout above the upper band or below the lower band to enter a trade in the direction of the breakout.

Combining Bollinger Bands with Other Indicators

To enhance trading strategies, Bollinger Bands can be combined with other technical indicators such as Relative Strength Index (RSI), Moving Average Convergence Divergence (MACD), and volume analysis. This combination helps confirm signals and reduce the likelihood of false predictions.


A trader might use Bollinger Bands in conjunction with RSI to identify overbought or oversold conditions. If AAPL’s price moves below the lower band and the RSI indicates an oversold condition, it could be a strong buy signal.

Practical Application in Coding

import pandas as pd
import numpy as np
import matplotlib.pyplot as plt

# Example data for AAPL stock prices
data = {'Date': pd.date_range(start='1/1/2023', periods=20, freq='D'),
        'Close': [150, 152, 153, 151, 149, 148, 147, 146, 145, 144, 143, 142, 141, 140, 139, 138, 137, 136, 135, 134]}

df = pd.DataFrame(data)
df.set_index('Date', inplace=True)

# Calculate the 20-day SMA
df['SMA_20'] = df['Close'].rolling(window=20).mean()

# Calculate the standard deviation
df['STD'] = df['Close'].rolling(window=20).std()

# Calculate the Bollinger Bands
df['Upper Band'] = df['SMA_20'] + (2 * df['STD'])
df['Lower Band'] = df['SMA_20'] - (2 * df['STD'])

# Plotting the Bollinger Bands
plt.figure(figsize=(10, 6))
plt.plot(df['Close'], label='AAPL Close Price')
plt.plot(df['SMA_20'], label='20-day SMA', color='orange')
plt.plot(df['Upper Band'], label='Upper Band', color='green')
plt.plot(df['Lower Band'], label='Lower Band', color='red')
plt.fill_between(df.index, df['Upper Band'], df['Lower Band'], color='gray', alpha=0.2)
plt.title('Bollinger Bands')

This code calculates the Bollinger Bands for AAPL stock prices and plots them, providing a visual representation of potential support and resistance levels.


Bollinger Bands are an invaluable tool in technical analysis, helping traders filter out market noise and identify potential trading opportunities. By understanding and utilizing Bollinger Bands, traders can enhance their trading strategies and make more informed decisions. Whether used independently or in combination with other indicators, Bollinger Bands provide valuable insights that can help traders navigate the complexities of the financial markets.

In summary, mastering Bollinger Bands requires practice and a deep understanding of market dynamics. As traders become more proficient in using Bollinger Bands, they can better anticipate market movements and achieve their investment goals. Integrating Bollinger Bands into your trading strategies can significantly enhance your ability to predict market trends and optimize your trading performance.

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