ADX / DMI (directional movement)
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Definition
The Directional Movement system plots +DI and -DI (upward vs. downward directional pressure) and ADX, a single line (0-100) that measures trend strength regardless of direction.
How to read it
ADX quantifies strength, not direction: below ~20 signals no/weak trend (range/chop), above ~25 signals a trend, and above ~40-50 a strong trend. Direction comes from the DI lines: +DI above -DI means bullish control, -DI above +DI means bearish. A rising ADX means the current trend (whichever DI is on top) is strengthening; a falling ADX means it is weakening even if price still drifts. DI crossovers can act as directional triggers.
How practitioners use it
Used as context among multiple indicators — never as a standalone signal to act.
Less common professional uses
ADX is a lagging, doubly-smoothed measure; it tells you a trend exists after it is underway and says nothing about direction, so it must be paired with the DI lines or price. Buying just because 'ADX is rising' with no direction check is a common misuse. A very high ADX often marks late-stage/climactic trends near exhaustion, not a fresh entry - high ADX is a reason to manage risk, not to chase. Using ADX as a conditioning variable (regime filter) rather than a signal is where it adds the most edge: it decides which strategy family to run, not which trade to take.
Sources & provenance
Wilder 1978
This page is educational content published by Pachira Aquatica Global LLC. It is not investment advice and not a recommendation.