Sizing by volatility means expressing the stop as a multiple of ATR rather than fixed pips, and letting the position size follow from it, so that risk in money is constant while the stop in price adapts to the regime. When volatility doubles, an ATR stop doubles and the position halves; the loss at the stop is unchanged. The same multiple sets a trailing exit — the Chandelier form subtracts three ATRs from the highest high — and the same logic scales targets. It does not change how often a given multiple is hit.
Sizing by volatility means placing the stop as a multiple of ATR rather than a fixed number of pips, and deriving the position size from it, so that the money at risk is constant across regimes while the stop in price adapts to them. When volatility doubles, the stop doubles and the position halves. The loss at the stop is unchanged.
The two parts before this one measured volatility and showed that it moves in regimes. This part is what a setup does about it — and it is the mechanical answer to a problem every earlier level circled: a rule written in pips was written in some regime, and the regime changed.
A fixed stop in two regimes
Take the setup from the Intermediate level with a 30-pip stop, and run it in a quiet market and a loud one.
The left stop is beyond the swing that invalidates the trade, as Foundations asked. The right stop is the same number of pips and is inside the ordinary range of a single bar. Nothing about the idea changed; the unit it was written in stopped meaning what it meant.
The stop as a multiple of ATR
The fix is to write the stop in volatility units. An ATR stop is placed a multiple of the current ATR from the entry — one and a half, two, whatever the setup’s testing settled on — and the multiple, not the pip count, is the rule.
Two things about the multiple.
It is still placed beyond the invalidation. The ATR multiple is a floor, not a replacement for structure. A stop that is one and a half ATRs away and beyond the swing low does both jobs; one that is one and a half ATRs away but inside the swing is a stop inside the pool with a volatility label on it. Where the two disagree, the structural level wins and the multiple says whether that level is realistic in this regime.
Which ATR is part of the rule. Part 8 ended on the lookback: a 14-bar ATR and a 100-bar ATR give different stops after a spike. The setup names one, on the timeframe it trades, and tests with it.
Size follows the stop
The stop distance is now a moving quantity. The position size has to move with it, and the way it moves is the position sizing arithmetic Foundations started with: money at risk divided by stop distance in price.
The figure’s numbers are illustrative — one per cent of a 10,000-unit account, on a pair where a lot is worth ten a pip — and the calculator does the division for any real values. What is not illustrative is the relationship. A volatility-adjusted size is what falls out when a fixed money risk meets a stop that scales with the regime: lots go down when the range goes up, and the amount at risk never moves.
This is also the honest version of the Intermediate level’s correlated positions arithmetic. Two positions that are “the same size in lots” in two instruments with different volatility are not the same risk; two positions sized so that one ATR of adverse movement costs the same money are.
Key takeaway The stop is written in ATR, the size is derived from the stop, and the money at risk is the constant. When the regime changes, the pip distance and the lot size change together, in opposite directions, and the thing the plan actually promised — how much a loss costs — stays exactly where it was.
Trailing by volatility: the Chandelier Exit
The same multiple can trail. The Chandelier Exit, developed by Charles Le Beau, hangs a stop a multiple of ATR below the highest high since the trade began — by default the 22-period high minus three times the 22-period ATR for a long, and the mirror for a short.
This is the structural trail of the Intermediate level with the distance made explicit. That part warned against trailing a fixed few pips, because a fixed distance sits inside the noise; the Chandelier’s distance is the noise, measured, times a multiple, which is why it holds through ordinary pullbacks and exits on ones larger than the regime produces. Three is Le Beau’s default; the setup’s own testing decides whether it is the right number for the timeframe and the instrument.
The target scales for the same reason. A 4.5-ATR target against a 1.5-ATR stop is 3R in every regime. A 90-pip target against a 30-pip stop is 3R in the regime it was written in and something else everywhere else.
What it changes, and what it does not
What volatility sizing does not do is worth saying plainly, because it is often sold as more than it is. A stop at one and a half ATRs is hit about as often in a loud regime as in a quiet one — that is what scaling with the noise means. The losing runs in the record, and the drawdown they add up to, are properties of the setup and arrive in every regime. What changed is that a loud regime no longer produces larger losses, and a quiet one no longer produces a position too small to matter.
That is the whole claim: constant money risk, regime by regime. It is enough to make a record from one regime readable in another — and reading records is what the next group is about.
Next: Expectancy with error bars — the standard error and confidence interval of a record’s expectancy, and how many trades it takes to tell an edge from zero.
- An ATR stop is a multiple of the current ATR, so it widens when volatility rises and tightens when it falls.
- Position size is derived from the stop distance and a fixed money risk; a wider ATR stop means a smaller position for the same risk.
- When volatility doubles, an ATR-based stop doubles and the position halves; the loss at the stop is unchanged.
- The Chandelier Exit sets a trailing stop at the 22-period high minus three times a 22-period ATR.
- Volatility-adjusted sizing keeps money risk constant across regimes; it does not change how often a given multiple is hit.
