2.5 Measures of Risk and Performance Flashcards
Semi-variance
- average squared deviations below the mean
(Σ of all Rt below the mean [Rt - E(R)]^2) / T - 1
Semi-standard Deviation
- sq. root of the semi-variance
Tracking Error
- extent to which investment returns deviate from the benchmark returns over time
√ (Σ ((Rt - Rb) - M)^2 / T - 1)
Where Rb is benchmark return, M is mean difference between investment return and benchmark return
Parametric VaR
= z * σ* √days * value
z = critical value for one-tailed test σ = std dev of daily returns √days = sq root of the number of days specified Value = value of investment portfolio
Z-values
90% VaR: use z-value of 1.28
95% VaR: use z-value of 1.65
99% VaR: use z-value of 2.33
VaR Calculation
- measure of potential loss ie: worst possible loss under normal conditions, over a specified period, for a given confidence level
Aggregating VaR - perfect positive correlation
VaRp = VaR1 + VaR2
Aggregating VaR - perfect negative correlation
VaRp = VaR1 - VaR2
*cancel each other out with diversification
Aggregating VaR - zero correlation
VaRp = √VaR1^2 + VaR2^2
Sharpe Ratio
- expected return (in excess of the risk free rate) per unit of total risk (σ)
(E(Rp) - Rf) / σp
- use for total portfolio, not components
Monthly Sharpe Ratio
[(E(Rp) - Rf) / 12] / σp/√12
Treynor Ratio
- expected excess return earned per unit of systematic risk
TR = (E(Rp) - Rf) / βp
Sortino Ratio
- expected excess return for a portfolio over a target return divided by target semi standard deviation
= (E(Rp) - Rt) / TSSD
Information Ratio
IRp = (E(Rp) - Rbenchmark) / Tracking Error of portfolio
Return on VaR
RoVaR = E(Rp) / VaR