Definitions
In plain terms
A constant close window produces a valid zero-width channel after warm-up.
Technical
The middle and bands remain ready, but Percent B is unavailable because its upper-minus-lower denominator is zero.
Scope
Collapsed bands are not the same as missing bands or a guaranteed future expansion.
Examples
- A reviewer traces Collapsed Bollinger Bands from aligned inputs through its first-ready row and edge cases before accepting a displayed value.
Common misconceptions
- Collapsed bands are not the same as missing bands or a guaranteed future expansion.
Concept relationships
Where this concept is used
Evidence and governance
- Bollinger Bands Rules John Bollinger · first party methodology
Supports: preferred label, short definition, technical definition
Limits: Interpretive rules do not prove forecasting power, trade profitability, or one universal parameter selection.
- TA-Lib Bollinger Bands TA-Lib · first party technical publication
Supports: preferred label, short definition, technical definition
Limits: TA-Lib permits moving-average variants beyond the local close-SMA and population-deviation contract.
- Reviewed by
- fintech-builder-batch-009
- Last reviewed
- 2026-07-30
- Next review
- 2027-07-30
- Record status
- published