Aroon indicator
Aroon measures how recently a stock made its 25-bar high and low, on twin 0–100 scales — a trend gauge built entirely from the timing of extremes, ignoring the size of any move.
Aroon asks the simplest trend question on record: when was the last extreme? Aroon-up reads 100 if the 25-bar high was set today and decays toward 0 as that high ages; Aroon-down does the same for the low. The oscillator is up minus down, spanning −100 to +100. No prices enter the calculation beyond finding the extremes — Tushar Chande built it purely from elapsed time, on the logic that uptrends keep making fresh highs and let old lows go stale.
The classic bullish configuration is Aroon-up above 70 with Aroon-down below 30: a new 25-bar high inside the last week or so, and the last 25-bar low ancient history. Both lines low together means neither extreme is recent — a drifting, rangebound stock — which makes Aroon a serviceable chop detector as well. On daily NSE bars it complements return-based momentum scans precisely because it ignores magnitude: a stock grinding out small new highs scores as well as one leaping to them.
That indifference to magnitude is also the trap. A stock that inches to a marginal new high by one rupee pins Aroon-up at 100 exactly as a 10% breakout does, so Aroon can read maximum trendiness on a chart going nowhere in price terms. The lines are also stepwise and jumpy — a single new extreme snaps a line to 100 — and the fixed 25-bar window means one old spike aging out of the lookback can move the reading with no new information at all.
Against ADX, the other trend gauge here, the split is recency versus magnitude: ADX measures how much directional ground price covers, Aroon only when the extremes happened. Aroon turns faster and is the cruder instrument; the pair disagreeing usually means new highs are arriving without much force behind them.
In Sift
Written as aroon_up, aroon_down, aroon().osc. A working scan — stocks with a fresh 25-bar high on the books and no recent low in sight:
where aroon_up > 70 and aroon_down < 301
of the 500 most-traded NSE stocks match today, as of 20 Aug 2026
Scans that use it
Prebuilt scans in the library whose query reads this value — each with a hit-rate replay over the last 250 sessions.
Common questions
What do Aroon-up and Aroon-down measure?
Elapsed time since the extremes. Aroon-up is 100 when the highest high of the last 25 bars was set today, falling toward 0 as that high ages; Aroon-down does the same for the lowest low. High up with low down reads as an uptrend; both low means no recent extreme either way — a drifting market.
Is Aroon a leading or lagging indicator?
Faster-lagging, honestly. It reacts the moment a new extreme prints, which makes it quicker than smoothed gauges like ADX, but it still only reports what price has already done. Its known blind spot is magnitude — a one-rupee marginal high scores identically to a 10% breakout — so it is usually read alongside a measure that sees size.