CVaR (Conditional Value at Risk)

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Expected Shortfall. How bad the bad days are, on average — not just where the threshold is.

Quick Answer

What is CVaR (Conditional Value at Risk)?

CVaR (Conditional Value at Risk, also called Expected Shortfall) is the expected loss given that the loss exceeds the VaR threshold. If 95% VaR is −3%, CVaR(95%) tells you the average loss in the worst 5% of cases — typically −5% or worse. Mathematically coherent in ways VaR is not.

CVaR_α = E[Loss | Loss > VaR_α]

Formula

CVaRα = E[Loss | Loss ≥ VaRα]
Expected value of loss conditional on the loss exceeding the VaR threshold.

Sort losses worst to best. Take the worst (1 − α)-fraction. Compute their average. That is CVaR.

Intuition — what is this number telling you?

VaR tells you where the threshold is. CVaR tells you how bad it gets beyond that threshold. Two portfolios with the same VaR can have very different CVaR — one might have a sharp threshold, the other has fat tails extending far past it.

CVaR satisfies subadditivity (combining two portfolios cannot increase total CVaR) and is therefore mathematically coherent. Basel III prefers CVaR for capital adequacy calculations.

Worked example

Step-by-step

Over 1000 daily returns, the 50 worst (5%) have an average of −4.1%.

Daily CVaR(95%) = −4.1%

The 95% VaR threshold was −2.3% (see VaR example). CVaR(95%) is much worse because the tail extends past the threshold.

What's a good CVaR (Conditional Value at Risk) value?

CVaR is always more negative than VaR (or equal). The ratio CVaR/VaR reflects tail-fatness: a normal distribution has CVaR(95%)/VaR(95%) ≈ 1.25; equity markets typically run 1.4–1.8; crypto can exceed 2.0.

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Related metrics

Value at Risk (VaR)  ·  Expected Shortfall  ·  CDaR (Conditional Drawdown at Risk)  ·  Kurtosis

Frequently asked questions about CVaR (Conditional Value at Risk)

How is CVaR different from VaR?

VaR is a threshold; CVaR averages the losses beyond it. CVaR captures tail severity that VaR ignores.

Why is CVaR preferred by regulators?

Because it is mathematically coherent — combining two portfolios cannot increase total CVaR (subadditivity). VaR can violate this.

What is "Expected Shortfall"?

Same thing as CVaR. Different name used in academic literature and Basel regulations.

Does Foliolytic compute CVaR?

Yes — at the same confidence levels as VaR.

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