TOPIC 5 - DIVERSIFICATION AND PORTFOLIO RISK Flashcards
Market risk (systematic risk) features
1) attributable to market-wide risk sources
2) remains even after diversification
firm-specific risk
risk that can be eliminated by diversification
diminishing marginal reduction in risk occurs from
increasing portfolio diversification
expected return of a portfolio made of equity and debt
rp= wdE(r)d + weE(r)e
w = weight in the asset
just a weighted average
covariance is used in portfolio theory to determine what assets to include to reduce the overall risk for a portfolio. It’s a
statistical measure of the directional relationship between 2 asset prices.
+ve covariance =
assets generally move in same direction
-ve covariance =
assets generally move in opposite directions
modern portfolio theory uses covariance how
optimises returns by including assets in their portfolio that have a -ve covariance
covariance helps investors create a portfolio that includes a mix of distinct asset types, thus employing
a diversification strategy to reduce risk
what does modern portfolio theory aim to do?
attempts to determine an efficient frontier for a mix of assets in a portfolio.
the efficient frontier aims to optimise the maximum return vs the degree of risk for the overall combined assets in the portfolio.
In MPT the goal is is to choose assets that have a
lower SD for the combined portfolio than the SD of the individual assets to reduce portfolio’s volatility.
MPT seeks to create an optimal mix of
higher volatility assets with lower volatility assets.
By diversifying assets in a portfolio, investors can reduce risk and still allow for a positive return.
what sort of relationship must assets have with eachother to be selected for a portfolio?
a negative covariance.
Analysts use historical price data to determine the measure of covariance between different stocks. This assumes that the same statistical relationship between the asset prices will continue into the future, which is not always the case.
drawbacks of using covariance to reduce portfolio risk
1) can only measure the directional relationship btw 2 assets.
- -> can’t show the strength of relationship btw assets. (correlation coefficient a better measure of that strength)
another drawback of covariance in terms of its calculation
2) calculation of covariance is sensitive to higher volatility returns –> more volatile assets incl returns that are farther from the mean (outlying returns can have undue influence on resulting covariance calc)
MPT is a theory on:
a) how risk-averse investors can construct portfolios to maximize E(r) based on a given level of market risk.
b) can also be used to construct a portfolio that minimises risk for a given level of E(r)
what does MPT recommend in terms of correlation coefficients? 1
1) that an investor measure the correlation coefficients between the returns of various assets in order to strategically select those that are less likely to lose value at the same time.
By measuring the orrelation coefficients between the returns of various assets in order to strategically select those that are less likely to lose value at the same time WHAT DOES THIS MEAN?
determining to what extent the prices of the assets tend to move in the same direction in response to macroeconomic trends.
what do you use correlation coefficients to do in MPT?
seek a 0 or near 0 correlation in price movements of the various assets in a portfolio.
This means seeking assets that respond to macroeconomic trends in distinctly different patterns.
covariance vs correlation
Covariance tells you that 2 variables change the same way
Correlation: reveals how a change in one variable affects a change in the other.
Diversification works best when assets are
uncorrelated or negatively correlated with one another, so that as some parts of the portfolio fall, others rise.
When it comes to diversified portfolios, correlation represents the
degree of relationship between the price movements of different assets included in the portfolio.
correlation of 1 =
perfectly +vely correlated –> asset prices move in tandem
correlation of -1 =
prices move in opposite directions
perfectly -vely correlated
correlation of 0 =
uncorrelated –> price movement of one asset has no effect on the price movement of the other asset.
different macroeconomic factors affect
different assets differently!
Not all assets created equal
Statisticians use price data to find out how the prices of two assets have moved in the past in relation to each other. Each pair of assets is assigned a
number that represents the degree of correlation in their price movements. This number can be used for constructing what is called a “correlation matrix” for different assets
How does a correlation matrix make task of choosing dif assets easier?
presenting their correlation with each other in a tabular form. Once you have the matrix, you can use it for choosing a wide variety of assets having different correlations with each other.
once you’ve got a correlation matrix, what do you do
start with broad categories (asset classes - stocks, bonds, gov securities etc, then narrow down to subclasses - consumer goods, energy tech etc).
What is the risk in terms of correlation and using levergae?
using leverage to make investments cuts both ways.
The strategy of taking high exposure by using borrowed money is good at increasing upside potential, but increases exposure to downside risk. You have to pay back the money that you owe from some other source.
When price of an asset is collapsing, the level of leverage may
force a trader to liquidate even his good assets. When a trader is selling his good assets to cover his losses, he hardly has time to distinguish between correlated and uncorrelated assets. He sells whatever is there in his hands.
our optimal risky portfolio is found from
the Sharpe Ratio (portfolio’s risk premium (rp - rf)/SDp
trying to find weights of D and E that give the highest slop of the CAL