Study the double bottom as a defined sequence of swings, then record both confirmed and failed exits with the same rules.
Identify the swings and the boundary
A double bottom contains two distinct troughs in approximately the same price zone, separated by a meaningful rebound. The intervening high forms the confirmation level. Two adjacent lows in one downswing are one test of support, rather than two separate bottoms. Set a price tolerance and minimum separation before collecting examples.
Read the formation in its preceding trend
The reversal interpretation begins with a decline. The second low shows another test of the earlier low, but the trend has not reversed merely because that test holds. The rebound high must also be reclaimed. A W-shaped pause during an advance has different preceding context.
Use an explicit confirmation rule
This example uses a close above the intervening high. A brief touch of that high leaves the formation unresolved. A subsequent retest that holds above it supports the new structure, while a return below it deserves review.
| Measure | Value |
|---|---|
| Confirmation session (first bar is session 1) | 41 |
| Boundary | 58.00 |
| Confirming close | 59.00 |
| Formation extreme | 50.00 |
| Formation height | 8.00 |
| Geometric objective | 66.00 |
Height = |50.00 − 58.00| = 8.00
Objective = 58.00 + 8.00 = 66.00The objective illustrates a measuring convention. It supplies no probability, expected return or evidence that a trade reaches that price. Keep the projected level separate from the actual chart observations and from a written risk plan.
Compare volume on the same daily basis
Compare each swing and the confirming session with this stock’s own daily volume. Quiet activity around a base and expansion on an exit are conventional context, but they do not establish direction or identify who traded. An event can dominate a single volume bar.
| Measure | Value |
|---|---|
| Confirmation volume | 220.00 |
| 20-session average including confirmation | 106.25 |
| Relative volume | 2.07× |
Including the current session in the average differs from dividing by the prior 20 sessions. An intraday comparison at the same clock time uses another denominator. State which one you use before comparing examples.
An exit that does not persist
The failure drawing briefly exceeds the intervening high, then loses it and closes below both lows. The earlier support tests did not establish a lasting reversal. Include this false breakout in the sample instead of rejecting it retrospectively as an imperfect W.
Distinguish nearby formations
A triple bottom contains a third distinct test. An inverse head and shoulders has a middle trough materially lower than both shoulders. Equal-looking lows should not be relabelled as shoulders merely to suggest a stronger reversal.
Keep a reproducible research record
Apply the same swing definition and boundary rule to every chart in a sample. Formations become visible as later bars confirm swings, so preserve the date on which each observation was knowable.
- Record the preceding trend, candle interval, price scale and corporate-action basis.
- Label the swings and write a boundary rule before viewing the later path.
- Record the confirming close, subsequent retest and the price that invalidates the premise.
- Compare volume on a named denominator and retain failed exits as well as resolving examples.
- Review earnings and other events, execution costs and gap risk separately from the geometric drawing.
These formations are studied by reading charts. A list of stocks near a high or low does not identify this pattern.
Sources
- Edwards, Magee and Bassetti, Technical Analysis of Stock Trends, 11th edition: reversal formations and measurement conventions
- StockCharts ChartSchool: Double bottom (checked October 1, 2026)
Read our data and methodology notes for calculation context. This guide explains research tools and observations. It does not recommend a trade or investment.