Chapter 15 Flashcards
What is a dominant investment strategy
One with the same level of risk but a greater expected return
What does ex ante mean
Risk and return calculated before investing period
Ex post meaning
Actual value ps after investing period
Most common risk measure for securities and portfolios
Ex post Standard deviation
Limitations of standard deviation
Based on historical prices so may not represent future
Measure of upside movement and downside, only concerned about downside
Assumes upside equally likely as downside
Vol is not the only risk, inflation risk is example of alternative risk
Alternative risk measures
Semi variance
Probability of shortfall
Expected shortfall
What is semi variance
Only measures returns in period that go below the mean - downside measure of risk
What is a probability of a shortfall
Probability of return falling below target level
What is expected shortfall
Measure of expected loss at a given probability level
Example in 5% worst cases, the firm loses 5 million
When does standard deviation understate the risk
When there is any form of auto correlation present in returns
What VaR (value at risk)
Used to estimate the capital loss on a portfolio or individual asset over a given time period that will be exceeded with a given frequency or probability
3 key features of VaR
Time period
Confidence or prob level
Loss amount/percentage
If a portfolio has a value of 100mn and we expect it to lose 10mn in one occasion out of 100 in 24 hrs then what is the var
1/100 = 1%
Var in this occasion is 99%
3 ways to calibrate Var
Historical returns
Variance covariance method
Monte Carlo approach
If the lowest 1% of daily retruns is all below minus 5% then what is var and explain
Var is 99% confidence that the worst daily loss will not exceed 5%
Losses of greater than 5% occur 1% of the time.
What assumption does variance covariance method for var use
Assumes returns are normally distributed
What does fat tails mean
Probability of extremes occur more commonly than predicted by distributions
Var limitation
Not a reliable guide to future losses
Sd (monthly) formula=
Sd (daily) x sqrt(time)
= Sd (daily) x sqrt(20)
20 bd in month average
Average trading days in a year
250
What is stochastic model and example of one
Vehicle for estimating probability distributions of the range of potential outcomes by allowing random variation in inputs over time
Monte Carlo
Deterministic model what is it
Output is determined by the parameter values and initial conditions
Drawdown
Decline in price form historical peak value of an investment, max amount of investment that could have been lost when at highest price
Limitations to drawdown
Longer the time series, the more likely to have a large drawdown
Max drawdown is a single number and will therefore have a large uncertain error distribution