Option Window · Foundations
Free to readReading the Curve: Level, Wings & Skew
Four shapes carry almost everything the Option Window has to say. Learn them and the chart reads in a second.
The Window is a single curve: percent change in the normalized, constant-30-day price across moneyness. Its shape tells you what was repriced. Here are the four you'll see most.
The four signatures: flat (nothing repriced), a parallel lift or drop (level — broad vol bid or crush), wings moving (tail risk repriced), and a steepening left side (skew widening). Most real days are a blend.
Level — the parallel move
When the whole curve lifts or drops together, the market repriced level — overall vol got more or less expensive across the board. A broad lift is a vol bid (often fear entering); a broad drop is a vol crush (often relief after a feared event passes). This is the VolDex® story, seen as a one-day change.
Wings — the tails
When the far-OTM ends move differently from the body, the market repriced the tails. Wings lifting means crash or melt-up protection is being bid; wings dropping means tail fear is draining and the far options are getting cheaper. This is the TailDex® story in motion.
Skew — the tilt
When the left side moves more than the right — puts repricing up relative to calls — skew is widening. The reverse, a right side catching up, is skew flattening (or a call bid, as in a squeeze). This is the Slope / RiskDex® story as a daily change.
Parallel move = level (vol bid or crush). Wings = tails. Left-vs-right = skew. Read which one dominated and you know what the market actually repriced today.
The framework is free. To read live shapes on a name: ETFs with ETF Analytics, single stocks with ETF + Equities, full surface via Everything.
See plans →Educational content from Nations Indexes. VolDex®, RiskDex®, and TailDex® are registered marks of Nations Indexes. Diagrams are schematic. Nothing here is investment advice.