Guide
SigmaRange does not tell you whether a stock is cheap. It tells you how much of the move its own options were priced for has already happened — and that is a different question, with a different use.
Mechanics
Three inputs, one of which changes every week and two of which do not move at all once the week starts.
Friday's regular-session close. It is fixed for the whole week — the band does not roll forward, and Wednesday is measured against the same price Monday was.
The 1σ move the options market prices for the week ahead, as a percentage of the anchor. It comes from implied volatility, not from past returns, so it widens before an earnings week on its own.
Distance from the anchor divided by that width. One number, on the same scale for every symbol, which is what makes a $9 name and a $900 name comparable at all.
Worked example
A stock closes Friday at $200 and its options price a ±5% week. That makes the anchor $200, the lower edge $190 and the upper edge $210. Then $205 reads +0.50σ, $210 reads +1.00σ and lands on the above-1σ list, and $185 reads −1.50σ and is called oversold. The same arithmetic runs on every symbol, which is why one board can hold both a $9 stock and a $900 one.
Reading
Five states, and the board never uses any others. The thresholds are the same ones the upstream weekly alert scores against.
More than 1.5 standard deviations above the anchor close. Statistically stretched to the upside.
Broke the upper 1σ edge of its expected range but has not reached the overheated threshold.
Inside the expected range. No statistical dislocation.
Broke the lower 1σ edge of its expected range but has not reached the oversold threshold.
More than 1.5 standard deviations below the anchor close. Statistically stretched to the downside.
Limits
The most expensive way to use this board is to read a band edge as an instruction.
−1σ means buy
It means the fall is already larger than the week was priced for. That happens because something changed, and the something is usually still true tomorrow.
+1σ means sell
Strong trends spend whole weeks outside the upper edge. A band tells you the move is unusual, not that it is finished.
A wide band means bullish
Width is a statement about range, not direction. A ±12% band says the options market expects a big week either way.
The band reacts to news
It is struck once, on Friday. An earnings miss on Tuesday does not widen it — which is exactly why a reading can run to −2σ and keep going.
Confluence
The one screen on this site that does not come from the band alone — and the reason a level here is worth more than a round number.
Neither is derived from the other. When they land on the same price, the level is corroborated rather than restated — which is the only reason the screen exists.
Call the result a reaction zone, not support. Gamma is a position, and positions change — the level can be gone by Thursday.
Case study · SNDK
Sandisk, band window Aug 24 – Aug 28, 2026. The −1σ edge and the week's dominant gamma strike landed 0.16% apart — close enough that on a chart they are one line.
Monday
$1,416.56
−1.10σ · through both levels
The week opened six percent below the anchor and kept going. The low printed under the gamma strike inside the first hour — and was the only print of the week below it. The close came back to $1,493.12, −0.63σ. On a daily candle the level held.
Tuesday
$1,564.99
+10.5% off Monday's low
The session traded up to $1,564.99 before giving back more than half of it. That is the whole case for watching a confluence zone: not that it predicted a bottom, but that the reaction when price reached it was large enough to be worth being early for.
Friday
$1,435.61
−0.98σ · tested again
Price came back to the same shelf four sessions later, stopped five dollars above the strike, and closed the week at $1,484.98 — −0.68σ, inside the band. Twice tested, twice held on a closing basis.
The honest part
The screen only looks at strikes near spot, so it did not name SNDK until the 2026-08-25 board — after Monday's test, not before it. The gamma was already there on Monday's settlement, and it was the largest positive-gamma strike anywhere below spot, but price had not yet come close enough for the screen to see it. That is the shape of the tool: it narrows a board of 123 names down to the few worth watching, and it does not time anything. Had the week gone the other way, the same two lines would have broken and this would be an example in the section above.
Workflow
Top down, and never starting with the individual name — a symbol at −1σ means something different on a day when forty others are too.
Reference
Every page reads the same snapshot and the same band. They differ only in what they select.
FAQ
Because the band was just struck. Friday's close becomes the new anchor, so until the market trades again every symbol sits exactly on it by construction. On that day the board is showing the range for the week ahead, not a result.
From the option-implied move for the week ahead, converted into a true 1σ before it reaches this site. Nothing here derives a band from past price movement.
The ones from a statistics class. About 68% of outcomes land within ±1σ, 87% within ±1.5σ, 95% within ±2σ and 99.7% within ±3σ. One side is half of what is left over: past +1σ is roughly one week in six, past +1.5σ one in fifteen, past +2σ one in forty. Those are the odds the options market priced, not a law of nature — real returns have fatter tails than the bell curve, so the extremes show up somewhat more often than the table says.
Most feeds quote the at-the-money straddle scaled by about 0.85, which is roughly a 0.68σ move — the range price stays inside about half the time. A 1σ range is the one price stays inside about 68% of the time, so it is about 1.47 times wider. It is a unit conversion, not a safety margin.
A strike below spot where dealers hold enough positive gamma that hedging it means buying into weakness. It is derived from open interest, not from implied volatility, which is why a gamma strike landing on the −1σ edge counts as corroboration rather than the same number said twice.
No. It means the move is bigger than the week was priced for. A σ reading measures how unusual a move is; it says nothing about what comes next.
Prices refresh through the session. The band itself is struck once a week from Friday's close and stays fixed until the next one.
No. Everything here is a measurement of published market data, offered as a way to decide what deserves a closer look.
Band window Sep 25 – Oct 2
Anchored on the Sep 25 close.