Trendlines and Channels
A straight line through successive highs or lows, describing the slope of a move. Useful, and more subjective than almost anything else on a chart.
MadStockAlerts Research · Updated August 28, 2026
What to take away
- An uptrend line connects rising lows; a downtrend line connects falling highs.
- Two points define a line and a third is what tests it.
- A price channel adds a parallel line on the other side of the move.
- A break of a trendline says the slope changed, not that the trend reversed.
- The drawing choices are unconstrained, so the evidence is weak taken alone.
MAD Academy Training Video · 0:44
The Line You Draw Is a Hypothesis
A trendline is not found on the chart, it is proposed by you — which is why the honest version is drawn before the move, not after.
This lesson is part of a Stock Alerts + Tools plan.
Drawing one
An uptrend produces higher lows, and a line drawn along them describes the rate at which buyers are stepping in earlier each time. A downtrend produces lower highs, and a line along those describes the rate at which sellers are appearing sooner.
Two points are enough to draw a line, and any two points define one. The third touch is what makes it worth anything, because until then the line describes nothing that could have been falsified.
The slope itself is information independent of the touches. A very steep line describes an advance that is unlikely to continue at that rate, because sustaining it requires accelerating demand indefinitely. Steep lines break; that is what steep means.
The subjectivity
Wicks or bodies? Include the outlier low or ignore it? Logarithmic scale or linear? Every one of those choices changes the line, and none of them has a correct answer. Two competent analysts drawing the same trend will produce two different lines, which is why a trendline break is weak evidence taken alone.
One partial discipline: draw the line that requires fewest exceptions, and use the same convention every time so that at least the inconsistency is your own and is stable. A trendline convention that never changes produces comparable drawings over time even if it is not objectively right.
Scroll the chart sideways to see all of it.
The other discipline is drawing the line before the test rather than after it. A line drawn after price bounced will always look like it caused the bounce.
Channels
A parallel line on the opposite side of the move creates a price channel, describing both where pullbacks have stalled and where advances have. It converts a single boundary into a range, which is more information for the same drawing effort.
When price stops reaching the far side of a channel, the trend is decelerating before any line has been broken. That is one of the few genuinely early observations available from a drawn construction, because it happens while the trend is still intact.
What a break means
A trendline describes a rate of advance. Breaking it means the rate changed, and a trend can slow into a sideways range and then resume without ever reversing. Treating a trendline break as a reversal conflates deceleration with a change of direction.
A more informative reading is to watch what happens after the break. A move that breaks a steep line and then forms a flat base has decelerated into a consolidation; one that breaks the line and then makes a lower low has changed structure.
What a break does and does not establish
A trendline break is widely treated as a signal that a trend has ended. What it establishes is narrower and worth stating precisely: price is no longer rising at the rate the line described.
A trend that decelerates breaks its line and continues. A trend that pauses breaks its line and resumes. A trend that ends also breaks its line, which is why the observation feels reliable in hindsight and performs poorly in advance. The break distinguishes none of these three cases at the moment it happens.
| What happens after a break | How common | What it was |
|---|---|---|
| Price continues up at a slower rate | Very common | A deceleration |
| Price moves sideways, then resumes | Common | A pause |
| Price reverses | Less common | The case the signal is named for |
| Price breaks, then reclaims the line | Common | Noise, or a line drawn slightly wrong |
The horizontal level is the more informative of the two drawings for this reason. A horizontal support break says price is below a price where buyers previously appeared, which is a statement about a fact. A trendline break is a statement about a rate, and rates change constantly without trends ending.
Channels, and what the width is doing
A channel is a trendline with a parallel line drawn at the other extreme of the move. The second line is not independently derived: it is placed to contain the price action, which means it carries whatever arbitrariness the first line had, plus one more choice.
- The parallel is usually anchored to the single most extreme point, which makes the whole channel depend on one bar.
- A channel drawn to contain everything will contain everything, which is a property of how it was drawn rather than a finding.
- Price reaching the upper boundary of an ascending channel is often described as overbought, and it is a description of where a drawn line sits.
- Channel width is a crude volatility measure, and ATR measures the same thing without the drawing.
The construction is most defensible when it is treated as a rough envelope rather than as a set of levels. A price outside the envelope has moved further from the trend than usual, which is a real observation, and it is the same observation a standard-deviation band provides more objectively.
The general point across every drawing in this pillar holds here too: a line that was fitted to the data cannot then be used as evidence about the data. What makes a channel worth anything is having drawn it before the bars it now contains.