Conditional VaR (CVaR) — tail risk pro management
JP Morgan 1994 RiskMetrics introduced VaR. ALE 2008 GFC: VaR fail capture tail risk. Lehman + AIG losses far beyond VaR. Result: Basel III 2024 standardize CVaR (Conditional VaR / Expected Shortfall). Captures average loss beyond VaR. Tail risk insurance. Pokazujemy framework retail adaptation.
Co to CVaR
CVaR = Expected Shortfall = ES. Average loss given that loss exceeds VaR threshold. Mathematically: E[L | L > VaR_α].
VaR limitations
„VaR fail captures: 1) Black Swan events (Lehman 2008, COVID 2020), 2) Fat tails (forex distributions), 3) Correlation breakdown (crisis times), 4) Extreme outliers. CVaR fixes."
Calculation
Retail adaptation:
- Historical 100+ trades P&L
- Sort worst to best
- VaR 95% = 5th percentile worst
- CVaR 95% = average of 5 worst losses
- CVaR > VaR always
Marek case
Trader application
- Position sizing: budget CVaR (NIE VaR)
- Stress testing: weekend gap, central bank surprise
- Hedge planning: options budget vs CVaR exposure
- Capital allocation: max CVaR/account ratio
Tools
- Excel: simple percentile calculation
- Python: NumPy, Pandas (free)
- R: ES function (free)
- RiskMetrics (commercial)
- Top: 100+ trade history baseline
Common mistakes
- Using VaR alone (tail risk hidden)
- Small sample size (< 60 trades)
- NIE stress test scenarios
- Position sizing CVaR ignored
Wnioski
CVaR (Conditional VaR / Expected Shortfall) = average loss beyond VaR. Tail risk capture.
VaR limitations: Black Swans, fat tails, correlation breakdown, outliers. CVaR fixes.
Calculation retail: 100+ trades, sort, VaR = 5th percentile worst, CVaR = average 5 worst.
Marek case: VaR -€200, CVaR -€350 = 75% larger tail. Position sizing budget CVaR.
Application: position sizing, stress testing, hedge planning, capital allocation.
Tools: Excel percentile, Python NumPy, R ES function. 100+ trade baseline.
Common mistakes: VaR alone, small sample, NIE stress test, position sizing CVaR ignored.
Konkluzja: CVaR upgrade vs VaR alone. Basel III 2024+ banking standard. Retail adaptation = budget worst 5% historical losses. Black Swan protection.
Powiązane: VaR podstawy, risk management, weekend gap.
Głębsza analiza — CVaR deep dive ForexMechanics.
Źródła i bibliografia
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BIS Basel III CVaR standard · Banking regulation www.bis.org ↗