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October 22, 2026FrançaisEspañol

Buying tail and selling tail: what they are, and how to test them

A buying tail is a wide bar with a long lower wick: price was pushed down hard during the minute, then bought back up before the close. A selling tail is the mirror image. Unlike a hammer, the bar has to be wide compared with the bars before it. Here is the exact rule QuantLogic uses.

wick ≥ 1/3 of rangeBuying tail
The level the idea readsThe bar where the idea firesA drawn example, not market data.

What it is

The tail is the wick. A long lower wick on a big bar shows a fast push down that did not hold by the close.

Size matters here: the same shape on a tiny bar is not counted, because the bar must be at least twice the usual size of the bars just before it.

The exact rule QuantLogic uses

Buying tail, on one-minute bars. The selling tail is the mirror image.

  1. The bar's range is at least twice the average range of the 20 bars before it.
  2. Its lower wick is at least 33% of its range.

When is it known? Known when the bar closes. The average uses only the 20 bars before it, so it needs 20 earlier bars.

Versions you can build

  • Buying tail. A wide bar with a lower wick of a third of its range or more.
  • Selling tail. A wide bar with an upper wick of a third of its range or more.

What to look at around it

In QuantLogic, every time the idea happened is laid out with the data points around it, so you can see where it held and where it didn't:

Time of day and sessionEconomic calendar and newsVWAP distanceGamma regime, flip and wallsYesterday's value area and pivotsVolatilityNQ vs ES since the openUp or down on the day

Traps when you test it

  • Counting small bars. The rule needs a bar twice the usual size; a small wick on a quiet minute is not a tail.
  • Reading the colour. A tail counts whether the bar closed up or down.
  • Testing one side only. Check the selling tails too.

Build it and test it yourself

Open Buying tail in Build with QuantLogic. See every time it happened on NQ, ES, Gold or Crude since September 2025, check the long and the short side, add your own filters and run the luck test.

Build this setupSee plans

Nothing is proven until it holds live. We give no trading signals and no advice, we never hold your money or your accounts, and we never trade for you.

Questions

What is the difference with a hammer?
A hammer is about the wick against the body, whatever the bar's size. A tail needs a wide bar, twice the recent average range.
Can a bar be both a buying and a selling tail?
Yes, a very wide bar with long wicks on both sides can match both rules.

Related setups

Educational content, not investment advice. Futures trading involves substantial risk of loss. See the risk disclosure.