Lecture 2 Flashcards
What is correlation
Correlation measures how returns move in relation to each other. It is between +1 (returns always move together) and -1 (returns always move in opposite way)
Skewness
Skewness for a normal distribution is zero, and any symmetric data
should have a skewness near zero
• Negative values for the skewness indicate data that are skewed left
• Positive values for the skewness indicate data that are skewed right
Positive and negative Kurtosis
- Positive excess kurtosis indicates a “peaked” distribution
- Negative excess kurtosis indicates a “flat” distribution
Leptocurtic Distribution
Leptocurtic Distribution - K > 3
A distribution with wide tails and a tall narrow peak is called leptokurtic
Compared with a normal distribution, a larger fraction of the returns are at the
extremes rather than slightly above or below the mean of the distribution
Platykurtic Distribution
Platykurtic Distribution - K
Which returns are better Leptocurtic or Platykurtic
Leptocurtic
Why Leptocurtic Returns?
- Low probability of extreme outcomes
- Regulatory process (e.g. managed exchange rate) dampens moderately
deviant returns, forcing them closer to the mean than they would have been
otherwise
Simple diversification
- Invest an equal amount in each of N assets
• Portfolio weight 1/N - Select the assets randomly
- The portfolio is well-diversified if N is reasonably large and fully
diversified if N → ∞
More advanced diversification
- Pick assets and determine optimal weights using the variance
covariance structure of the returns
• Exploits the trade-off between risk and return by using a
maximizing criterion – e.g. expected utility maximization
Why Portfolio variance equals
the average covariance
- Gauges the systematic risk
that affects all assets - Unique risk (individual variances)
diversified away
Diversification
Strategy designed to reduce risk by spreading
the portfolio across many investments.
Unique Risk
Risk factors affecting only that firm
- Also called “diversifiable risk”
Market Risk
Economy-wide sources of risk that affect the
overall stock market
- Also called “systematic risk”
- Reason why stocks have a tendency to move together – common factor affecting all stocks
What does correlation measure
Correlation measures how returns move in relation to each other