Risk Flashcards
Features of Equity Returns
- Rarely IID
- Heteroscedasticity
- Volatility Clustering
- Leptokurtic
Less Pronounced over Long Periods (over-optimism/pessimism corrections however)
Features of Portfolio Returns
- Correlations Between Series at Given Time
- Correlations Vary Over Time
- No Cross-correlation (t and t+1)
- Cross-correlation between squared/absolute value returns
- Increased dependence during high volatility periods
Less Pronounced over Long Periods (over-optimism/pessimism corrections however)
Modelling Market Returns
- Historical Simulations (Boostrapping)
- Forward Looking
- Data (multi-variate normal, other joint distribution or copula - 6-step)
- Factor (PCA 10-step)
6 Step Forward Looking Data Approach Market Risk
- Decide Frequency (daily, weekly, monthly)
- Time frame for historical data (volume vs relevance)
- Choose Return Index
- Evaluate log returns
- Calculate average returns, variances and covariances
- Simulate Series of Returns
10 Step Forward Looking Factor Approach Market Risk
Dim Red, Assumes Normal Distribution,
- Decide Frequency (daily, weekly, monthly)
- Time frame for historical data (volume vs relevance)
- Choose Return Index
- Evaluate log returns
- Calculate average returns, variances and covariances
- Derive Matrix of Deviations From Average
- Derive Principle Components Sufficient To Explain Deviation
- - Power method (V1* = SigmaV, then V = V1/maxval)
- - Normalise dividing by V’V
- - Subtract eigenvalue*VV’ from Sigma
- - Repeat - Create i.i.d. random variables using eigenvalues as variance (X = VLZ + u)
- Weight by elements of eigenvectors.
- Add weighted projected deviances to expected returns.
Market Risk Under Basal II
Internal model 10-day 99% VaR
Credit Spread Reflects …
- Expected probability of, and loss given default
- Uncertainty of Above (risk premium)
- Liquidity Premium
Three ways of measuring credit spread
- Nominal Spread (GRY risky less risk free)
- Static Spread (addition to risk free spot rates to have discounted cashflows equate to price)
- Option adjusted spread (stochastic models to adjust for embedded options)
Expected Return on Other Asset Classes
Consider:
- Historical Risk Premiums
- Alter allowing for expected future changes
- Subjective
- Based on fundamental structural changes in asset class
- Consistent Approach with CAPM
Properties of Good Benchmark (6, 7)
- Unambiguous
- Investable and Trackable
- Frequently measurable
- Appropriate to Objectives
- Reflects current sentiment
- Specified in advance
Optional, - Contains portion of assets in portfolio
- Similar investment style to portfolio
- Low constituent turnover
- Investable portion sizes
- p(rx - rm, rb - rm)»_space; 0
- p(rx - rb, rb - ru)»_space; 0
- Variability of portfolio returns relative to benchmark should be lower than variability relative to market return.
Benchmark Risk Types
- Strategic Risk: Poor performance of benchmark
- Active Risk: Poor performance of portfolio relative to benchmark
- Active return: Return relative to benchmark
Steps in PCA approach of interest rate risk
- Decide on frequency
- Decide on time frame
- Take GRYs for bonds of different durations and calculate average interest rate for series
- Deduct average interest rate (derive deviation)
- Set of factors chosen and weighted, then projected using independent random normal varaibles to produce expected interest rates for each term.
Exchange Rate Equation
e_0(1 + Ry,T)/e_T = 1 + Rx,T
Where Ry,T is return in foreign currency.
e_0 is amount in foreign currency for 1 unit of domestic.
Assessing Contagion Risk
- Suitably parameterised copula to model interaction between series’, particularly at extreme negative values.
- T-Copula with situation-dependent correlation parameter
- Sealer correlation effects ignored due to arbitrageurs.
Brennan-Schwartz Model
r1,t = (a_1 + b(r2 - r1))deltaT + rE r2,t = ((a2 + b2r1 + cr2)r2)DeltaT + r2E