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Bollinger Bands

A moving average with a band that widens and narrows with volatility.

3 min · Intermediate · Lesson 10 of 12

Step 1 of 4

Three lines

Bollinger Bands draw a 20-day moving average with an upper and a lower band two standard deviations above and below it. Standard deviation measures how widely prices have been swinging, so the bands widen when prices are jumpy and narrow when they're calm.

SPY$498.56down 1.74 percentvs. start of period

SPY price chart, 3M: $498.56, down 1.74 percent versus the start of period.

Dashed line: start of period. Regular-session prices.

Turn on Bollinger Bands under Indicators on a stock's chart to see them.

For entertainment and education, not investment advice.