Stochastic Oscillator: the Current Bar Belongs in the Range by Definition, and %D Alone Has One Valid Signal
%K = 100 x (Price - Low_N) / (High_N - Low_N), where High and Low are the extremes of the last N periods. %D is an N-day moving average of %K. Developed by George Lane in the late 1950s.
★The current bar is inside the range by definition
The formula is **%K = 100 x (Price - Low_N) / (High_N - Low_N)**, and the source defines the bounds plainly: **"High and Low are the highest and lowest prices in the last 5 days respectively"** in the five-period example. ★**The window is the last N periods, which includes the period being evaluated.**[1]
★**This matters for anyone testing the indicator.** With some indicators, using the current bar's high and low to compute that bar's value is a mistake — the value ends up describing the bar it is being compared against. ★**Here it is not a mistake: the definition places the current bar inside the range.** A %K that excluded the current bar would be a different indicator. ★**This page does not survey how platforms implement it**, only what the definition says.[1]
A related structural point: ★**the window is fixed.** Because %K reads the highest and lowest prices of N periods rather than an exponentially weighted average, ★**the value does not depend on how much history preceded the calculation.** ★**This is a contrast drawn by this page, not a statement in the source**, and it distinguishes the stochastic from indicators built on smoothed averages.[1]
★%D is where implementations diverge
**%D is "the N-day moving average of %K (the last N values of %K)"** — a smoothing of the raw line. And the source immediately flags the ambiguity: ★**"Usually this is a simple moving average, but can be an exponential moving average for a less standardized weighting for more recent values."** ★**So two platforms can both be correct and still disagree** — a comparison should state which one it used.[1]
★**And the source restricts what %D alone can be used for.** **"There is only one valid signal in working with %D alone — a divergence between %D and the analyzed security."** ★**By the reference's own account, reading %D on its own for anything other than divergence is outside what it endorses.** The usual construction pairs the lines: an alert exists **"when the %D line is in an extreme area and diverging from the price action"**, and **"the actual signal takes place when the faster %K line crosses the %D line."**[1]
Parameters are conventions, as elsewhere in this family. **"Typical values for N are 5, 9, or 14 periods"** and **"smoothing the indicator over 3 periods is standard."** The article also describes a three-line variant giving **"an anticipatory signal in %K, a signal in the turnaround of %D at or before a bottom, and a confirmation of the turnaround in %D-Slow."** ★**Three named lines, three different roles** — answers that treat "the stochastic" as one line lose that.[1]
★The premise is stated as a tendency, not a proof
The reasoning behind the indicator is written out. ★**"The idea behind this indicator is that prices tend to close near the extremes of the recent range before turning points."** The price is then **"expressed as a percentage of this range with 0% indicating the bottom of the range and 100% indicating the upper limits of the range over the time period covered."**[1]
★**"Tend to" is the source's wording and is kept here.** The article presents this as the premise the indicator is built on, ★**not as a demonstrated regularity**, and it offers no test of it. ★**Whether acting on the resulting signals produces a profit is not addressed by this page, which carries no backtest figures.**[1]
One further reading is named. A **"stochastic pop" occurs "when prices break out and keep going"**, interpreted as a signal to **increase the current position, or liquidate if the direction is against the current position.** ★**That is the opposite response to the mean-reversion reading** of an extreme %K — ★**the same indicator supports both, and the article does not choose between them.**[1]
What this page has not established
★**This page rests on one institution — a single Wikipedia article — with no independent cross-check.** ★**Lane's own writings, cited by the article (including "Lane's Stochastics", Technical Analysis of Stocks and Commodities, 1984), were not read.** ★**Investopedia, a usual second reference for this topic, returned HTTP 402 on 2026-09-23 and could not be read.**[1]
★**Not established:** the numeric levels conventionally treated as overbought or oversold for this indicator, how %K is seeded for the first N-1 periods, what "%D-Slow" is smoothed over, whether 5/9/14 outperforms other settings, and how far the stated premise holds empirically. The article notes **Williams %R is "equivalent of %K, mirrored around the 0%-axis"**; ★**this page did not verify that relationship.** **As of 2026-09-24.**[1]
Verified facts
Cross-checked against 2+ independent sourcesThis section contains facts cross-checked against multiple sources.
Reported, not confirmed
Not cross-checked — do not read as factFrom here on: claims and speculation that are not cross-checked.
The stochastic oscillator is "a momentum indicator within technical analysis that uses support and resistance levels as an oscillator", and "George Lane developed this indicator in the late 1950s".[1] single-source ×1 · Wikipedia Stochastic oscillator, opening paragraph
%K = 100 x (Price - Low_5) / (High_5 - Low_5), "where High and Low are the highest and lowest prices in the last 5 days respectively, while %D is the N-day moving average of %K (the last N values of %K)".[1] single-source ×1 · Wikipedia Stochastic oscillator, definition section
On the smoothing of %D the article states: "Usually this is a simple moving average, but can be an exponential moving average for a less standardized weighting for more recent values."[1] single-source ×1 · Wikipedia Stochastic oscillator, definition section
The article states: "There is only one valid signal in working with %D alone — a divergence between %D and the analyzed security."[1] single-source ×1 · Wikipedia Stochastic oscillator, definition section
The premise is stated as "prices tend to close near the extremes of the recent range before turning points", with the price expressed as a percentage of the range, "0% indicating the bottom of the range and 100% indicating the upper limits".[1] single-source ×1 · Wikipedia Stochastic oscillator, calculation section
"Typical values for N are 5, 9, or 14 periods" and "smoothing the indicator over 3 periods is standard".[1] single-source ×1 · Wikipedia Stochastic oscillator, calculation section
An alert is present "when the %D line is in an extreme area and diverging from the price action", while "the actual signal takes place when the faster %K line crosses the %D line".[1] single-source ×1 · Wikipedia Stochastic oscillator, interpretation section
A "stochastic pop" is described as occurring "when prices break out and keep going", interpreted as a signal to increase the position or liquidate if the direction is against it.[1] single-source ×1 · Wikipedia Stochastic oscillator, interpretation section
Crossovers and extreme readings are conventionally treated as trading signals, but whether acting on them produces a profit is not addressed by this page.[1] single-source ×1 · Scope limitation of this page — editorial, not sourced
Timeline
- 1950
George Lane develops the stochastic oscillator in the late 1950s (decade marker).[1]
- 1984
Lane publishes "Lane's Stochastics" in Technical Analysis of Stocks and Commodities (cited by the source; not read by this page).[1]
- 2026-09-24
Reference date for this page. The Wikipedia article was read on this day.[1]
- Model
- claude-opus-5
- Time
- 09/24/2026, 00:30
- Tokens
- 12,000
- Sources
- 1 sources adopted
- Model
- operator
- Time
- 09/24/2026, 00:30
- Tokens
- 5,000
- Verdict
- Passed
Show revision history (2)
| 09/24/2026, 00:30 | First authored (claude-opus-5) | Created |
| 09/24/2026 | First draft (steadytrade PM #16 request, 8 of 8) | Updated |
Frequently asked
Does %K include the current bar in its high-low range?
Yes, by definition. The source says High and Low are the highest and lowest prices in the last N periods, which includes the period being evaluated. A %K excluding the current bar would be a different indicator.[1]
Is %D a simple or exponential moving average?
Either. The source states it is usually a simple moving average but can be an exponential one for a less standardized weighting of recent values, so implementations can differ while both follow the definition.[1]
Can %D be used on its own?
Only narrowly. The article states there is only one valid signal in working with %D alone — a divergence between %D and the analyzed security. The usual signal comes from %K crossing %D.[1]
What are the standard parameters?
Typical values for N are 5, 9 or 14 periods, and smoothing the indicator over 3 periods is described as standard. These are conventions, not derived optima.[1]
What is a stochastic pop?
The article describes it as occurring when prices break out and keep going, interpreted as a signal to increase the position or liquidate if the direction is against it — the opposite response to reading an extreme as mean reversion.[1]