VIX Term Structure API

The shape of the equity volatility curve — the single most-watched regime signal in the options world — computed live from Yahoo Finance, no key, nothing stored. A VIX level tells you how scared the market is right now; the term structure tells you whether that fear is short-term panic or a calm, persistent state, and which way it is rolling. This API reads the S&P 500 implied-volatility curve across four tenors — the 9-day VIX, the headline 30-day VIX, the 3-month VIX and the 6-month VIX — and turns it into a regime. When the curve slopes up (VIX < VIX3M < VIX6M) the market is in contango: calm, with near-term vol cheaper than far, the state short-vol strategies harvest. When it inverts to backwardation (VIX above VIX3M) the front end is bid above the back: acute stress, fear spiking, historically near capitulation. The structure endpoint returns the live curve, the contango ratio (VIX / VIX3M), the short-end ratio (VIX9D / VIX), the roll yield a short-vol position would earn, the slope classification and a regime read, with VVIX (the vol of the VIX) for context. The history endpoint returns the daily time series of the contango ratio and flags every backwardation day. The percentile endpoint places today's contango ratio in its one-year range. This is the volatility term-structure / contango-backwardation cut — distinct from the cross-asset VIX-family level board, the crypto DVOL index and the realised-volatility APIs. It is the shape of fear, not its level.