When Fₑ exceeds 1.5, you are statistically buying into exhaustion. Here is the data behind the indicator and how to set your personal threshold.
The Extension Factor, Fₑ, is a deliberately simple idea: it measures how far the current price has moved from its recent mean, expressed in units of that stock's own typical volatility. A stock that's 1 standard deviation above its 20-day average has an Fₑ near 1.0. A stock that's stretched to 1.5x or beyond its normal range has an Fₑ above 1.5 — and that's the zone where our historical data shows the odds start turning against fresh long entries.
Why 1.5 specifically
We backtested entries across thousands of extension events and grouped them by Fₑ at time of entry. Below 1.0, forward 5-day returns were roughly neutral to slightly positive — the stock still had room to run. Between 1.0 and 1.5, results were mixed and highly dependent on sector and volume context. Above 1.5, the distribution shifted meaningfully: mean-reversion became the more common outcome over the following week, and the tail risk of a sharp pullback increased noticeably.
1.5 isn't a magic number so much as the point where the data stopped being ambiguous. It's the threshold where "this could still run further" statistically gives way to "this is now more likely to cool off than continue."
Setting your own threshold
Fₑ = 1.5 is our default, but it's a starting point, not a rule carved in stone. Momentum traders who are comfortable holding through volatility may reasonably push their personal threshold to 1.8–2.0, accepting more risk for the chance of catching a genuine breakout. More conservative, mean-reversion-oriented traders often tighten it to 1.2–1.3, preferring to sit out anything that looks stretched at all. The platform lets you set your own Fₑ alert threshold in Settings so the indicator matches your actual trading style rather than a one-size-fits-all default.