Assessing Whether SPX Options Are Expensive from Volatility Forecasts
Summary
The article frames the cost of SPX options as a comparison between option-implied volatility and a forecast of future volatility. It suggests treating options as expensive when the forecast is well below the implied level, and cheap when the forecast is well above it. The examples are presented as a way to assess portfolio hedges, especially put protection, rather than as a standalone trading system.
The forecast assumptions include persistence around recent volatility, gradual reversion toward a long-run average, and faster reversion after an unusual uncertainty event has passed. It also notes that volatility tends to rise when the index falls, a relationship relevant to hedging. The excerpt gives no actual forecast, measured option prices, backtest, or detailed calculation, so it does not establish whether SPX options were cheap or costly at the time. These heuristics are therefore context for analysis, not evidence of a reliable valuation edge.
Key ideas
- Compare forecast future volatility with implied volatility to judge option richness or cheapness.
- Options may appear expensive when forecast volatility is materially below the implied level.
- Recent volatility can persist, while longer-run mean reversion may occur gradually.
- An exceptional uncertainty shock that has passed may be followed by faster volatility normalization.
- SPX volatility tends to move inversely to the index, affecting the value of put hedges.
Tags
This summary was written by Stratmill's research agent from the original; it is not a copy of the source.