VIX and the Term Structure

VIX is the most-cited volatility number in markets, and the most misunderstood. It is one point on a curve, not the curve itself. The shape of the curve, the relationship between near-dated and longer-dated implied volatilities, says more about market state than any single tenor. This chapter is about reading the curve.

The term structure

Implied volatility exists for every expiration on the SPX chain. VIX is the most famous one because it standardizes a thirty-day forward calculation, but the same idea extends across horizons. VIX9D is the nine-day forward number. VIX3M is the three-month. VIX6M is six months. VIX1Y is one year. Plotted on the same axis, those tenors form a curve. The curve has a shape, and the shape changes with the state of the market.

Contango versus backwardation

The two extremes of the curve have names. Contango is the normal state: longer-dated IV is higher than shorter-dated. The curve slopes up. The market is saying that uncertainty grows with the horizon, which is intuitive (more time, more things can happen). Backwardation is the stressed state: shorter-dated IV is higher than longer-dated. The curve slopes down. The market is saying that the immediate uncertainty is greater than the long-run uncertainty. People are paying up for protection right now, more than they are paying for protection three months out.

The headline number to watch is the VIX basis, sometimes called the VIX term spread. It is VIX minus VIX3M. The sign and magnitude tell the regime.

• ▸VIX basis below zero: contango. The normal state. Markets are calm. Curve is upward-sloping.
• ▸VIX basis near zero: flat curve. Transition zone. Either calming down or building toward stress. Direction of change matters more than the level.
• ▸VIX basis above zero: backwardation. Crisis pricing in front-month options. Markets are paying more for short-dated protection than long-dated, which is structurally unstable.

Backwardation rarely lasts long. Either the stress dissipates and the curve re-steepens back into contango, or the underlying breaks and the implied volatility resets across the curve. The regime is, by construction, transitional.

VVIX: the vol of vol

VVIX is the implied volatility of VIX itself. Think of it as the option market's read on how violently VIX is expected to move. The thresholds are useful anchors. Between eighty and ninety, VVIX is calm and VIX itself is steady. Between one hundred and one-twenty, conditions are normal, VIX moves but not violently. Above one-thirty, VIX itself is jumpy. Elevated VVIX often coincides with backwardation in the term structure, and the combination tends to show up just before or during meaningful drawdowns. VVIX is the early warning sensor for the term structure's stability.

Curve over Level

A flat VIX of fourteen and a flat VIX of twenty-five tell almost the same story. A VIX of eighteen with the curve in backwardation and elevated VVIX tells a different one entirely.

Reading the regime through the curve

Three composite reads cover most market states. Steep contango with low VVIX is a quiet, steady tape. Long-gamma dealer regimes are probable. Range trading is favored. A flat curve sitting near the contango-backwardation line is a transition zone. Whatever the level, the direction the curve is changing matters more than the level itself. Backwardation with elevated VVIX is the stress regime. Trends extend. Breakouts become more likely. Dealer short-gamma positioning becomes probable. Fat-tail risk is real and pricing reflects it.

The two cleanest recent examples of regime-flip-via-curve happened six years apart. On February 5, 2018 the VIX doubled from a 17.31 close to 37.32 in a single session. The curve had been in deep contango for months, holders of short-volatility ETPs (XIV, SVXY, VMIN) had crowded the trade, and the term structure had quietly been flattening for weeks before the snap. The flip-into-backwardation lasted only a few days, but the unwind ended one of the most popular short-vol trades of the cycle. Six and a half years later, on August 5, 2024, a structurally similar pattern repeated at index level: contango through the summer, then a single overnight move that inverted the curve with VIX printing above 60. Both events shared the same curve signature in the weeks leading up. The trader who reads only the level of VIX cannot see those signatures coming. The trader who reads the curve can.

VIX is implied, not realized

VIX is a calculation derived from SPX option prices using a fixed methodology. It is not the actual standard deviation of SPX returns. It is the market's implied expectation, which can be (and frequently is) wrong. Realized volatility, the actual standard deviation of returns over a window, often runs lower than VIX in calm regimes (the volatility risk premium, the persistent edge that option sellers earn) and higher than VIX in crisis regimes (when option sellers are blown out and option buyers could not get enough hedge before the underlying moved). The gap between implied and realized is itself a tradable structure. This book does not chase that edge, but the reader should know it exists.

The previous chapters covered dealer positioning from multiple angles: gamma at strikes, walls, the regime line, charm and vanna across time and volatility. This chapter has zoomed out to the volatility curve itself. Together they form the picture of structure. The next part of the book moves from structure to signal: the regime classification, the direction call, and the conviction score that decide what the engine actually does with all of this.