The double bottom is a major reversal pattern that forms after an extended downtrend. As its name implies, the pattern is made up of two consecutive troughs that are roughly equal, with a moderate peak in-between.
Although there can be variations, the classic double bottom usually marks an intermediate or long-term change in trend. Many potential double bottoms can form along the way down, but until key resistance is broken, a reversal cannot be confirmed. To help clarify, we will look at the key points in the formation and then walk through an example.
With any reversal pattern, there must be an existing trend to reverse. In the case of the double bottom, a significant downtrend of several months should be in place. First Trough: The first trough should mark the lowest point of the current trend. As such, the first trough is fairly normal in appearance and the downtrend remains firmly in place.
After the first trough, an advance takes place that typically ranges from 10 to 20%. Volume on the advance from the first trough is usually inconsequential, but an increase could signal early accumulation. The high of the peak is sometimes rounded or drawn out a bit from the hesitation to go back down. This hesitation indicates that demand is increasing, but still not strong enough for a breakout.
The decline off the reaction high usually occurs with low volume and meets support from the previous low. Support from the previous low should be expected. Even after establishing support, only the possibility of a double bottom exists, it still needs to be confirmed. The time period between troughs can vary from a few weeks to many months, with the norm being 1-3 months. While exact troughs are preferable, there is some room to maneuver and usually a trough within 3% of the previous is considered valid.
Advance from Trough:
Volume is more important for the double bottom than the double top. There should clear evidence that volume and buying pressure are accelerating during the advance off of the second trough. An accelerated ascent, perhaps marked with a gap or two, also indicates a potential change in sentiment.
Even after trading up to resistance, the double top and trend reversal are still not complete. Breaking resistance from the highest point between the troughs completes the double bottom. This too should occur with an increase in volume and/or an accelerated ascent.
Resistance Turned Support:
Broken resistance becomes potential support and there is sometimes a test of this newfound support level with the first correction. Such a test can offer a second chance to close a short position or initiate a long.
The distance from the resistance breakout to trough lows can be added on top of the resistance break to estimate a target. This would imply that the bigger the formation is, the larger the potential advance.