Supertrend — the retail trader's favourite trend tool

The answer

Supertrend draws a single line above or below price and changes colour when price closes on the other side of it. The line is placed at a distance set by ATR, so it widens when the instrument is moving a lot and tightens when it is quiet.

That is the whole idea. It is a trailing stop that scales to volatility, which is a genuine improvement on a fixed percentage stop, and it is not a forecast.

Why this costs you money

Supertrend is the most popular indicator among Indian retail traders, and the reason is honest: it is the easiest thing on a chart to read. Green line below price. Red line above price. No interpretation required.

That readability is exactly what makes it expensive. An indicator that requires no judgement invites you to supply none.

Here is the specific loss. A stock enters a 6 week sideways stretch. Supertrend flips to green. You buy. Four days later it flips red. You sell and go short, because the tool is symmetric and it looks like it is telling you to. Two days later it is green again. In that 6 weeks you can take 6 trades and lose on 5 of them, each loss roughly the width of the band. If the band is 2.5% wide and you pay costs on 12 transactions, a stock that moved nowhere has removed 15% of the capital you allocated to it.

A trader who took no trades at all in that period finished ahead of you. The indicator did not malfunction. It did exactly what it is built to do, in the one environment where doing that is a losing activity.

How it works

Supertrend is built in 3 steps.

Step 1. Find the midpoint of each bar. Add the high and the low, divide by

1. This is sometimes written as HL2.

Step 2. Measure volatility with ATR. ATR is the Average True Range, the average size of a bar's full move over the last N bars, including any gap from the previous close. The default is 10 periods on most platforms. ATR was introduced by J. Welles Wilder Jr. in New Concepts in Technical Trading Systems in 1978.

Step 3. Place 2 bands. The upper band is the midpoint plus (multiplier × ATR). The lower band is the midpoint minus (multiplier × ATR). The default multiplier is 3.

Then a ratchet rule turns the 2 bands into 1 line. While price is above the line, the line only moves up, never down. It follows price higher and stays put during pullbacks. When a candle closes below the line, the line jumps above price, changes colour, and from then on only moves down. It flips again when a candle closes above it.

So the "signal" is a closing price crossing a level. The level is placed 3 ATR away from the middle of the recent bar and dragged along behind the move.

The credit for Supertrend is usually given to Olivier Seban, a French trader and author.

The 2 settings do exactly what you would expect:

There is no correct pair. Every reduction in whipsaws is bought with a later entry and a bigger giveback. That trade-off cannot be optimised away, only moved.

What it tells you, and what it does not

It tells you where a volatility-scaled trailing stop sits right now. That is real information, and it is better information than a 5% stop, because 5% means something different on a stock that moves 0.8% a day and one that moves 4% a day. Supertrend automatically knows the difference. Parabolic SAR does not.

It tells you which side of that stop price closed on. That is a summary of the recent past, correctly computed.

It does not tell you whether a trend exists. Supertrend has no measure of trend strength inside it. Its inputs are the bar midpoint and ATR. Neither of those answers "is this going anywhere".

It does not tell you the flip is a reversal. A flip means one closing price crossed one level. In a strong trend, a single wide down day is enough to close below a line that has been ratcheted up close to price.

And it does not tell you anything the price bar did not already say. This is the sentence that applies to this whole cluster. Supertrend is computed from the high, the low and the close. It contains no external information. What it does is convert "where is my stop, given how much this thing moves" into a line you can see, at the cost of a delay.

The decision rule

Treat the Supertrend line as a stop level, not as an instruction.

For exits: if you are long and price closes below the line, the trade is over on your rules. This use is defensible on its own.

For entries: require 2 things before acting on a green flip. First, a separate trend-strength reading — ADX above 25, or simply higher highs and higher lows on the weekly chart. Second, a flip that happens away from the middle of the recent range, not inside it.

Never reverse automatically. Closing a long and opening a short are 2 decisions. Supertrend collapses them into 1 because the line is symmetric. Symmetry in the drawing is not symmetry in the odds.

If you cannot say in one sentence why the flip mattered, other than "the line changed colour", you are trading a colour.

Try this now

Five minutes, on a stock you own or watch.

1. Open a daily chart, 1 year of data. Add Supertrend with the default settings, ATR period 10 and multiplier 3.
2. Count every colour change in that year. Write the number down.
3. Now measure the width. Pick any 5 days at random and measure the gap between the closing price and the Supertrend line, as a percentage of price. Average them. That is roughly what one flip costs you if you enter and exit on the line.
4. Multiply. Number of flips × average width gives you a rough total of the distance the strategy would have surrendered over the year, before costs.
5. Compare that number to how much the stock actually moved from January to December.

What you should see. On most single stocks you will find between 10 and 25 flips a year and a band width between 4% and 9% of price. The multiplication in step 4 usually produces a number larger than the stock's entire yearly move.

That is not proof the indicator is useless. It is proof of where the profit has to come from: a small number of large trends must pay for a large number of small flips. Now look at your chart and ask whether that stock produced 1 or 2 trends big enough to do it. On many stocks in many years, the honest answer is no.

Then change the multiplier from 3 to 5 and repeat step 2. Watch the flip count fall and the band width rise. You have just seen the entire trade-off in 30 seconds.

Three real cases

1. BANK NIFTY, 2022 — the popular chart, the difficult year Supertrend on BANK NIFTY is one of the most widely shared setups in Indian retail trading. In 2022 the index made a large net gain over the calendar year, but it did so through several sharp reversals rather than one clean move . On a daily chart with default settings, this is the pattern that produces a positive full-year return for a buy-and-hold position and a poor return for a flip-on-every-signal position, because most of the flips happened inside the reversals.

2. S&P 500, June to August 2022 — the counter-rally that flips a trend tool The US index fell through the first half of 2022. From mid-June to mid-August it then rose roughly 17%, before resuming the fall and making a lower low in October 2022. A default Supertrend, which had been red through the spring, flipped green during that rally and flipped red again after it. Both flips were correctly computed. Both were losses. A single indicator cannot distinguish a counter-trend rally from a new trend, because at the moment of the flip the 2 look identical.

3. J. Welles Wilder Jr., 1978 — where the useful half came from The part of Supertrend that does real work is ATR, and ATR is 1 of 4 tools Wilder published in a single 1978 book. The multiplier and the ratchet are a wrapper around it. This matters practically: if you find Supertrend useful, what you actually find useful is volatility-scaled distance, and you can use that directly for stop placement and position sizing without accepting the flip signals at all. Article 16 in this cluster does exactly that.

The question that resolves it

A novice sees a green Supertrend and asks: should I buy?

An expert sees the same green line and asks: how wide is the band right now, and can I afford to be stopped out at it?

The first question treats the line as a prediction. The second treats it as a price level with a cost attached. Only the second question has an answer, and the answer changes your position size before it changes your opinion.

What would make this wrong

If Supertrend flips carried predictive information, then a flip would be followed by a move in its direction more often than the base rate of the instrument, measured across many stocks over many years. Anyone can test this. The count in "Try this now" is the beginning of it.

The honest limits are 3.

First, this article assumes daily charts with default settings. Supertrend on a weekly chart of an index behaves very differently, because weekly bars filter out most of the noise that causes flips. If you test daily and trade weekly, or the reverse, you have learned nothing about the thing you are doing.

Second, judging a trailing stop by its win rate is the wrong test, and this article's exercise leans on flip counts. A rule that is right 30% of the time can be excellent if the 30% are much larger than the 70%. The complete test is total outcome after costs, not accuracy.

Third, Supertrend genuinely is better than a fixed percentage stop. Nothing here argues otherwise. The argument is against using it as an entry trigger, which is a different job.

Carry this

• Supertrend is ATR distance plus a ratchet. Nothing more is inside it.
• The colour tells you where price closed relative to a stop. It is not a forecast.
• Count the flips and measure the band on your own chart. The trade-off becomes obvious in 5 minutes.

Knowledge check

Related

• Parabolic SAR — the trailing-stop indicator
• ATR — Average True Range and volatility stops
• ADX and DMI — measuring trend strength
• Confluence and confirmation
• ← Indicators and confirmation