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Implied correlation measures the market's expectation of how correlated index components will move, derived from the relationship between index IV and component IVs. When implied correlation is high, options markets expect stocks to move in lockstep.
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Key takeawayHigh implied correlation (above 0.7) means index premium is relatively rich versus single-stock premium. Premium sellers benefit from selling index options in high-correlation regimes since the diversification benefit of the index dampens realized moves.
💡 Why It Matters
Implied correlation drives the relationship between index and single-stock option pricing. When implied correlation is high, index premium is relatively rich, and premium sellers should favor index options over single-stock options for better risk-adjusted returns.
⚙ How It Works
Implied correlation is derived from the relationship: Index IV^2 = Sum(weight_i^2 * IV_i^2) + Sum(weight_i * weight_j * IV_i * IV_j * corr_ij). Given known index IV and component IVs, you can solve for the average implied correlation. The CBOE Implied Correlation Index tracks this for the S&P 500.
📋 Example
The CBOE Implied Correlation Index reads 0.65 versus a 3-month realized correlation of 0.45. This 0.20 gap means the market is overpricing correlation, making SPX options relatively expensive versus component options. A premium seller focuses on SPX strangles rather than AAPL or MSFT strangles to exploit this premium.
⚠ Common Mistakes
Traders assume high implied correlation means stocks will move together. Implied correlation is a pricing input derived from options markets, not a forecast of future correlation. It is persistently higher than realized correlation because it includes a risk premium.
❓ FAQ
What is Implied Correlation?
Implied correlation measures the market's expectation of how correlated index components will move, derived from the relationship between index IV and component IVs. When implied correlation is high, options markets expect stocks to move in lockstep.
Why does Implied Correlation matter for premium sellers?
High implied correlation (above 0.7) means index premium is relatively rich versus single-stock premium. Premium sellers benefit from selling index options in high-correlation regimes since the diversification benefit of the index dampens realized moves.
How does Implied Correlation work?
Implied correlation is derived from the relationship: Index IV^2 = Sum(weight_i^2 * IV_i^2) + Sum(weight_i * weight_j * IV_i * IV_j * corr_ij). Given known index IV and component IVs, you can solve for the average implied correlation. The CBOE Implied Correlation Index tracks this for the S&P 500.
What are common mistakes with Implied Correlation?
Traders assume high implied correlation means stocks will move together. Implied correlation is a pricing input derived from options markets, not a forecast of future correlation. It is persistently higher than realized correlation because it includes a risk premium.
Related Terms
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CPI Print
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Dispersion Trading
Dispersion trading exploits the persistent premium of index implied volatility over the weighted average of its component implied volatilities.
This is not financial advice. Read our full investment disclaimer.