Term structure: volatility across time
Implied volatility is not a single number — it exists at every expiration, and stringing those points together gives you the volatility term structure: the market’s expected volatility over one week, one month, three months, and beyond.
Most of the time the curve slopes gently upward: near-dated volatility is lower than far-dated, because there is more uncertainty the further out you look. This normal shape is called contango, and it reflects a calm market that expects today’s conditions to persist in the short run. When the curve inverts — near-dated volatility spiking above far-dated — it is a warning: the market expects turbulence soon, and is paying up for immediate protection more than for distant risk. That inverted shape is called backwardation, and it tends to appear around shocks and sell-offs.
A worked example
On a quiet day, VolDex®-style readings might run 12 at one week, 15 at one month, 17 at three months — a smooth upward slope. Calm. Then a shock hits: the one-week reading leaps to 28 while the three-month barely moves to 18. The curve has inverted — the market is bracing for near-term turbulence even though its longer-run view is little changed.
TermDex® turns that whole shape into one number: the slope of the curve, read against the asset’s own history rather than a fixed threshold. Instead of eyeballing several tenors, you watch a single line move from “calm” toward “stressed.”
One more wrinkle: known events distort the near end of the curve. An earnings date, an FOMC meeting, or a CPI print concentrates expected movement on a single day, which creates a local bump in whichever expiration captures the event. Reading the term structure well means recognizing that bump for what it is — priced-in event risk — rather than mistaking it for a broad regime shift.
Common pitfalls
Reading only the 30-day point. A single tenor hides the slope, and the slope is where the regime signal lives.
Confusing a normal upward slope with “volatility rising.” Contango is the calm, default shape — not a warning.
Ignoring event bumps. A spike in the front tenor may just be a known earnings or macro date, not a change in the underlying regime.
The slope is not only a signal to read — it is something traders act on. In persistent contango, some sell richer near-dated volatility against cheaper far-dated; when the curve inverts, that trade can reverse violently. It is one reason inversions are treated as genuine regime events rather than noise.
What to do with this
Read both the level and the slope of implied volatility. Treat a gentle upward curve as normal, and a flattening or inversion as a live warning that near-term stress is being priced in — while accounting for event bumps at the front. TermDex® lets you track that slope as one moving line. The final lesson explains why a single blended gauge like VIX can’t give you any of this.
Next lesson · continue the courseThe problem with VIX — and a cleaner way →
TermDex® compresses the whole VolDex® curve into a single slope reading, tracked against each asset’s own history. Live inside ETF Analytics.