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Inputs
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Notes:
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Trading days /year
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252
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Initial portfolio value (W)
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$100
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VaR Time horizon (days) (h)
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10
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Asset returns/volatility are expressed annually, but our VaR will refer to a number of days. Selecting the time horizon is a design decision.
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VaR confidence interval
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95%
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The other design decision is the confidence (typically 95% or 99%). VaR is not the worst case scenario; VaR is the worst loss associated with a given probability.
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Asset A
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Volatility (per year)
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10%
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Expected Return (per year)
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15%
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Portfolio Weight (Asset A)
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50%
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Asset B
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Volatility
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20%
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Expected Return (per year)
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25%
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Portfolio Weight (Asset B)
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50%
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Correlation (A,B)
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1.00
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Outputs
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Solved Annual Metrics
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Covariance (A,B)
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0.0200
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Covariance = (correlation A,B)(volatility A)(volatiltiy B)
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Portfolio variance
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0.0225
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The key formula for two-asset variance; please make sure you know that we can substitute the covariance with (correlation A,B)(volatility A)(volatiltiy B)
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Expected portfolio return (per year)
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20%
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Expected return is simply weighted average expected return
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Portfolio volatility (per year)
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15.0%
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Portfolio volatility for the two-asset portfolio
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Solved Periodic (h days) Metrics
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Expected periodic return (u)
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0.79%
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Annual return scaled by time
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Standard deviation (h)
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2.99%
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The portfolio's annual volatiltiy scaled by the square root of time (the square root of time rule)
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z-value
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-1.64
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95.0% of the area under a normal curve is to the right of -1.64 standard deviations. Or, 5.0% is to the left.
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Expected future value
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100.79
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The portfolio value if it grows at the expected return over the period
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Relative VaR
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$4.91
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Basic (relative) dollar VaR: portfolio scaled by volatility (itself scaled by square root of time) and scaled by confidence (critical value)
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Absolute VaR
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$4.12
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Basic absolute dollar VaR: the loss from zero. This is less due to the expected (gain) return.
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