Volatility Term Structure and What Contango Signals

Volatility term structure runs from contango in calm markets to backwardation when near-term risk is priced above the risk sitting further out.

Volatility term structure is the curve formed by plotting implied volatility, or the equivalent VIX futures level, against time to expiry for a single underlying. The curve is in contango when longer-dated levels sit above shorter-dated ones, the resting shape for a calm market, and in backwardation when that order reverses, which signals that the market is pricing more risk into the near term than it is pricing into the months beyond it.

The clearest version runs through the at-the-money implied volatility of S&P 500 options at each listed expiry, one month, three months, six months and twelve months out, but the same shape shows up in the VIX futures curve, where each contract prices the market’s expectation for where the 30-day variance rate described in the VIX calculation will sit on that contract’s own settlement date.

The options curve and the futures curve usually move together, since both are pricing the same underlying variance, but they are not identical instruments and can separate modestly during stress, in the same way skew across strikes at one expiry is a related but distinct read on the same set of options.

Two forces keep the curve sloping upward most of the time. Uncertainty compounds with a longer window simply because more time means more opportunity for something to happen, so longer-dated implied volatility sits above shorter-dated implied volatility even before any change in market conditions. Specific to VIX futures, when the spot index trades below its own longer-run average, futures further out price in some reversion back toward that average, so a spot VIX at 14 can sit alongside a three-month future closer to 17, not because a shock is expected in three months specifically, but because 14 is read as unusually calm.

A representative contango shape might show spot VIX at 14, the front-month future at 15.5, the third-month future at 17 and the sixth-month future at 18, with each successive step smaller than the last as the curve flattens toward its long-run resting level.