Direct answer
A worked example of trendline breaks shows, step by step, how you draw a trendline, define what counts as a “break,” and apply that rule to a simple price sequence. The key is to state every assumption (how the line is drawn, what distance counts, how many time steps must remain beyond the line, and what data source rules you use). Without those assumptions, two readers can label the same chart differently.
Mechanism or definition
A trendline break is typically described as a situation where the market price that had been respecting a trendline moves to the other side of that line, and the move persists according to your chosen rule.
To make this precise for a worked example, you need assumptions:
- Trendline construction rule: For a short example, assume the trendline is defined by two “anchor” points (for example, a prior low and a later low for an uptrend, or two highs for a downtrend).
- Break rule: Decide whether a break means (a) the price touches beyond the line, (b) it moves beyond by a minimum distance, and (b) it stays beyond for multiple time steps.
- Data granularity: Decide whether you use closing prices, highs/lows, or another rule.
Because these choices are not universal, the same price movement can be “a break” under one rule and not under another.
Evidence or example (fully numerical, with stated assumptions)
Assume a simple rising trendline for illustrative purposes.
Assumptions (explicit):
- Time step size is 1 unit. We label points at t=0,1,2,3,4.
- We build an uptrend line using two anchor lows at t=0 and t=3.
- Anchor low values are P(t=0)=100 and P(t=3)=106.
- We therefore use a straight line with slope (106−100)/(3−0)=6/3=2 per time step.
- Trendline value at time t is: L(t)=100+2t.
- We define a trendline break as: the closing price is at least 0.5 units below the line (distance filter), and this condition holds for two consecutive time steps.
- No fees, spreads, execution timing, or future behavior are included; this is purely a chart-logic example.
Now consider the following closing prices:
- Close at t=0: 100
- Close at t=1: 103
- Close at t=2: 104.8
- Close at t=3: 105.8
- Close at t=4: 105.0
- Close at t=5: 104.4
Compute line levels:
- L(4)=100+2·4=108
- L(5)=100+2·5=110
Apply the break rule:
- At t=4, the distance below the line is L(4)−Close(4)=108−105.0=3.0, which is ≥0.5. Condition holds.
- At t=5, distance is L(5)−Close(5)=110−104.4=5.6, which is ≥0.5. Condition holds.
Because both t=4 and t=5 satisfy the distance filter and the two-step persistence requirement, this worked setup would label the move as a trendline break (under the specific assumptions listed above).
If instead you used a looser rule like “any touch of a line counts” or a different data field like “low price,” you might get a different label. That difference is why assumptions must be stated.
Limitations and risks (material failure modes)
- Ambiguous trendline drawing: Different anchor points or slightly different selection of highs/lows can produce different trendlines, changing whether a break is detected.
- Noise versus persistence: Requiring persistence (as in the example) reduces false labeling from a single time-step move, but it can also delay recognition.
- Rule dependence: “Break” is not a single universally defined event. Distance thresholds, which price you use (close vs. high/low), and how many steps must confirm are variable choices.
- No guarantee about what follows: Even when the break rule is applied consistently, outcomes can vary. Historical relationships do not automatically establish future results, and market conditions, liquidity, and costs can affect observed behavior.
Verification or next question
To independently verify a claim of a trendline break, you can reproduce the logic on the chart:
- Identify the two anchor points used for the trendline and compute the line equation.