Know Sure Thing Indicator: How Martin Pring’s KST Blends Four Speeds of Momentum

A single rate-of-change line is twitchy. Use a short lookback and it flips every few sessions; use a long one and it reacts after the move is half done. The know sure thing indicator, better known as KST, is Martin Pring’s answer to that problem. Instead of choosing one lookback, it takes four, smooths each one, gives the slower ones more say, and adds them up into a single momentum line with a signal line riding alongside.

That sounds complicated. It isn’t, once you see the pieces laid out. In this guide we’ll build the KST from scratch, run the numbers on a made-up NSE stock, go through the three ways traders read it, and then spend some time on the part most explainers skip: how much price history it needs and why its signals arrive late.

Where the know sure thing indicator comes from

Pring developed the indicator and introduced it in 1992 in Stocks & Commodities magazine, according to TradingView’s KST reference page. He originally called it the “Summed Rate of Change”. The KST name is the one that stuck, as the Investopedia explainer on the KST also notes.

The name is a bit of a joke, honestly. Nothing in technical analysis is a sure thing, and the KST is no exception. What it does offer is a cleaner read of momentum than any single rate-of-change line, because short-term noise gets outvoted by the longer cycles.

The building block: rate of change

Everything in the KST starts with the rate of change, or ROC. Investopedia’s guide to the ROC indicator gives the formula as:

ROC = [(Today’s close − Close n periods ago) ÷ Close n periods ago] × 100

So it’s just the percentage change in price over n periods. Readings above zero mean price is higher than it was n periods back; below zero means it’s lower. ROC has no upper limit, which matters later when we talk about overbought and oversold levels. If you want the full treatment of ROC on its own, our rate of change indicator guide covers it.

A quick example with hypothetical numbers. Say a stock closes at ₹1,150 today and closed at ₹1,100 ten sessions ago. The 10-period ROC is (1,150 − 1,100) ÷ 1,100 × 100, which works out to about 4.55. Price is roughly 4.55% higher than it was ten sessions back.

The KST formula, step by step

Both Investopedia and TradingView describe the same default daily recipe. You calculate four ROCs, smooth each with a simple moving average (SMA), then weight and add them:

• RCMA1 = 10-period SMA of the 10-period ROC
• RCMA2 = 10-period SMA of the 15-period ROC
• RCMA3 = 10-period SMA of the 20-period ROC
• RCMA4 = 15-period SMA of the 30-period ROC

KST = (RCMA1 × 1) + (RCMA2 × 2) + (RCMA3 × 3) + (RCMA4 × 4)

The signal line is a 9-period SMA of the KST itself.

On TradingView, these defaults show up as a string of nine numbers: 10, 15, 20, 30, 10, 10, 10, 15, 9. The first four are the ROC lengths, the next four are the SMA lengths applied to each ROC, and the last one is the signal line length. Once you know that, the settings box stops looking like a lottery ticket.

Look at the weights. The slowest component, the smoothed 30-period ROC, is multiplied by 4. The fastest is multiplied by 1. That’s the design choice that gives the KST its character: the longer price cycles dominate, and the short-term wiggles add colour without taking over.

The KST isn’t four indicators stacked on a chart. It’s one line where the slow cycles carry most of the weight and the fast ones get a smaller vote.

Worked example: building one KST reading

Let’s take a hypothetical stock, which we’ll call Sahyadri Cements. These are not real prices or readings; we picked round numbers so the arithmetic is easy to follow. Suppose that after doing the ROC and SMA work on its daily closes, we get these four smoothed values for today:

• RCMA1 (smoothed 10-day ROC) = 3.2
• RCMA2 (smoothed 15-day ROC) = 4.1
• RCMA3 (smoothed 20-day ROC) = 5.0
• RCMA4 (smoothed 30-day ROC) = 6.4

Now apply the weights:

• 3.2 × 1 = 3.2
• 4.1 × 2 = 8.2
• 5.0 × 3 = 15.0
• 6.4 × 4 = 25.6

Add them: 3.2 + 8.2 + 15.0 + 25.6 = 52.0. That’s today’s KST.

Here’s the bit we find most useful. Of that 52.0, the slowest component alone contributes 25.6, which is about 49% of the total. The fastest contributes 3.2, or about 6%. So nearly half the reading comes from the 30-day cycle.

What happens if the short-term picture suddenly sours? Say a weak week drags RCMA1 from +3.2 to −1.0 while the other three hold steady. The new KST is −1.0 + 8.2 + 15.0 + 25.6 = 47.8. That’s a fall of 4.2 points, roughly 8% of the earlier reading. The KST has noticed the wobble, but it hasn’t panicked. For a swing trader, that’s either a feature or a frustration, depending on which side of the trade you’re on.

Building the signal line

The signal line is a plain 9-period average of KST values. Continuing the hypothetical example, suppose the last nine KST readings were:

41, 44, 46, 49, 51, 52, 52.5, 51, 49

They add up to 435.5. Divide by 9 and the signal line sits at about 48.39. Today’s KST of 49 is still just above it.

Tomorrow the KST slips to 46. The oldest value (41) drops out of the window and 46 comes in, so the nine values now add up to 440.5 and the signal line moves to about 48.94. With the KST at 46, it has now crossed below the signal line while still well above zero. In TradingView’s framing, a positive KST crossing below its signal line means downside momentum is picking up. Notice that price could still be near its highs at this point. The crossover is a warning about momentum, not a statement that the trend has ended.

Three ways to read the KST

1. Signal-line crossovers

This is the most common use. Investopedia describes trading signals being generated when the KST crosses its signal line. TradingView adds a useful nuance: when the KST is negative and crosses above the signal line, upside momentum is increasing; when it’s positive and crosses below, downside momentum is increasing. Of the two crossover types, TradingView treats signal-line crosses as the ones that can flag an underlying change in momentum.

2. Zero-line crossovers

When the KST is above zero, the weighted momentum across all four cycles is positive. Below zero, it’s negative. TradingView’s general rule is simple enough: positive KST means momentum is up, negative means it’s down. The catch, which TradingView spells out, is that zero-line crossovers carry a lot of lag and aren’t always reliable. By the time a 30-day ROC smoothed over 15 sessions has flipped sign, a lot of the move is usually behind you.

3. Divergence

Divergence is when price and the indicator disagree. Bullish divergence: price keeps falling but the KST is rising. Bearish divergence: price keeps rising but the KST is falling. Both suggest the momentum underneath isn’t backing the price move. If divergence is new to you, our piece on RSI divergence walks through the same idea with a different oscillator, and the logic carries over.

Overbought and oversold: why there’s no magic number

With RSI, people talk about 70 and 30. You can’t do that with the KST. As TradingView points out, the KST isn’t bound to a fixed range, so there’s no universal overbought or oversold line. A KST reading of 52 might be stretched for a sleepy FMCG stock and perfectly ordinary for a high-beta PSU name.

The practical way around this is to look at the stock’s own history. Scroll back a couple of years and note where the KST tended to peak and trough. Those zones become your rough reference for that one stock. Even then, TradingView’s view is that extreme readings are more often trend confirmation than reversal signals: a very high KST in a strong uptrend is usually a sign of strength, not a sell signal by itself.

How much history does the KST need?

This is the practical detail that trips people up, especially with recently listed stocks. We worked it out from the default daily settings:

• A 30-period ROC needs 31 closes before it produces its first value.
• Smoothing that ROC with a 15-period SMA needs 15 ROC values, so the first RCMA4 appears on the 45th close.
• The other three components are ready earlier, so the first full KST reading also lands on the 45th close.
• The 9-period signal line needs nine KST values, so it first appears on the 53rd close.

In other words, on a daily chart you need about 53 trading sessions of data before you get a usable KST with a signal line. For a stock that listed six weeks ago, the indicator simply isn’t ready. Charting platforms may show a partial line earlier depending on how they handle the warm-up, so treat the first stretch of any KST plot with suspicion.

Before trusting a KST crossover on a fresh listing, count the sessions. On default daily settings, the signal line needs about 53 closes to exist at all.

Daily, weekly and monthly settings

The defaults above are for daily charts. TradingView notes that Pring recommended changing the parameters when you move to weekly or monthly charts, and it lists these sets:

• Daily: 10, 15, 20, 30 ROC lengths; 10, 10, 10, 15 SMA lengths; 9 signal
• Weekly: 10, 13, 15, 20 ROC lengths; 10, 13, 15, 20 SMA lengths; 9 signal
• Monthly: 9, 12, 18, 24 ROC lengths; 6, 6, 6, 9 SMA lengths; 9 signal

Using the same counting method as before, the weekly set needs 40 weekly closes for the first KST and 48 for the signal line. The monthly set needs 33 monthly closes for the first KST and 41 for the signal line, which is more than three years of data. That’s fine for an index or an old blue chip. It rules out most recent IPOs.

Where the KST lets you down

Every moving average adds delay, and the KST is built on five of them (four for the components, one for the signal line). TradingView is blunt about this: the lag is built in, and that’s why simple zero-line signals can be unreliable. On a stock that’s chopping sideways in a 5% range, you’ll see the KST and its signal line weave around each other and produce crossovers that go nowhere.

Gaps are another headache. Say a stock gaps up 8% on results day. That jump shows up in all four ROCs at once, and the slow components carry it for weeks. The KST can stay elevated long after the news has been priced in, simply because that one session is still sitting inside the 30-day window.

Investopedia’s advice is the sensible one: use the KST alongside other tools, such as chart patterns, candlesticks or volume, rather than as a stand-alone system. We’d add one thing. Because the KST and MACD are both momentum measures built from averages, pairing them mostly tells you the same story twice. A volume-based check or a clear support and resistance level adds more independent information.

A simple way to put it to work

Here’s one way a swing trader might use it, again with hypothetical numbers. Say the KST on Sahyadri Cements has been below zero for weeks, turns up, and crosses above its signal line while price holds above a support level at ₹1,095. The trader buys at ₹1,150 with a stop just under support at ₹1,095, so the risk is ₹55 per share.

With a trading account of ₹5,00,000 and a rule of risking no more than 1% per trade, the maximum loss allowed is ₹5,000. Divide ₹5,000 by ₹55 and you get about 90.9, so the position is 90 shares. That’s ₹1,03,500 of stock, with a worst-case loss of 90 × ₹55 = ₹4,950 if the stop is hit cleanly. Gaps can make the real loss bigger than that, which is one more reason to size from the stop rather than from conviction.

The exit can come from the KST too. A cross back below the signal line while the KST is positive is the first warning. Some traders tighten their stop at that point rather than selling outright, since the slow components may keep the trend alive for a while longer.

Quick checklist before acting on a KST signal

• Make sure the chart has enough history: about 53 sessions on default daily settings.
• Check which side of zero the KST is on. A cross above the signal line from below zero carries different meaning from one well above zero.
• Look at the stock’s own past KST extremes instead of assuming a fixed overbought level.
• Check for a recent gap, results date or corporate action that could be distorting the slower ROCs.
• Confirm with something that isn’t another momentum average: volume, a price level or a pattern.
• Size the position from the stop distance before you place the order.

For more on how indicators like this fit with price action, support and resistance and candlestick reading, see our technical analysis for Indian stocks guide.

Disclaimer: This article is for educational purposes only and is not investment advice. The stock name, prices, ROC and KST values and position size in the worked examples are hypothetical and were calculated by us to illustrate the formula. Indicator definitions and settings are summarised from the linked sources. Trading in stocks and derivatives involves risk of loss. Please do your own research and consult a SEBI-registered investment adviser before making any investment decision.