Flags and Pennants: Shapes and Failure Cases

Include the preceding move in the definition

A small channel is not automatically a flag, and every triangle is not a pennant. The prior move, often called the pole, provides part of the pattern's context. TradingView documents separate flag and pennant detectors, illustrating that the shapes require different boundary rules.

Terms such as sharp and short are relative. A reproducible rule should state the pole's minimum change and duration, consolidation duration, maximum retracement and allowed boundary slope. These need not be universal values; they need to remain fixed during a particular evaluation.

Compare two hypothetical consolidations

Assume price rises from 50 to 60 over five completed bars. It then forms highs of 59.5, 59.0 and 58.5 and lows of 57.5, 57.0 and 56.5 at evenly spaced pivot times. Similar downward slopes suggest a parallel flag-shaped consolidation after the advance.

For a pennant example after the same advance, suppose highs fall from 60 to 59 to 58.5 while lows rise from 56 to 57 to 57.5. The boundaries converge. The starting move is identical, but the consolidation geometry differs. A wider search algorithm may classify either example differently if its pivot timing or tolerance changes.

Now suppose price closes above the selected upper boundary and then quickly returns below the lower one. That is a failed continuation for a simple upward-break rule. It remains a relevant observation even if the later chart no longer looks like a textbook example.

Measured moves need explicit labels

Adding a pole's 10-unit height to a hypothetical break at 59 produces a projected level of 69. This is arithmetic based on a convention. It does not establish that price will cover that distance, that the projection is more likely than another, or that an order can fill at the breakout boundary.

Cost and timing matter when a consolidation is narrow. A spread that is small relative to the whole pole may be large relative to the proposed stop. Waiting for a confirmed close changes entry distance; entering during the bar introduces uncertainty about whether the break will remain visible at close.

Preserve all eligible examples

Record consolidations that expire without a break, break in the opposite direction or overlap with earlier candidates. Selecting only the examples that completed a measured move produces a misleading success rate. Keep pole selection, boundary coordinates and observation timestamps in a structured log.

Compare triangle conventions, check the actual entry-to-stop and target arithmetic, and read the overfitting reference. Recognizing a familiar shape is the start of defining a test, not the conclusion that the resulting trade has an advantage.