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RISK AND RETURN
RISK AND RETURN
Investors demand _______ for time and risk:
Compensation
Probabilities are between ___ and ___:
0 and 1
Probabilities must sum to....
1
A table of probabilities and outcomes is known as what?
A probability distribution
Distributions can be what two things?
1. discrete
2. continuous (like a normal distribution)
What is the formula for the mean or expected value of a discrete random variable X?
E(X) = prob1X1 + prob2X2 ....
1 = one possible outcome
prob = probability of that outcome
X = the return if outcome happens
The amount of dispersion in a graph of the probability distribution function is measured by what?
Variance and standard deviation
The ____ of a stock is the amount of dispersion in a graph:
Risk
- the more dispersion, the more risk
T or F: the standard deviation of individual stocks in a PORTFOLIO is a relevant measure of risk
False, the standard deviation is only a measure of risk for stocks that are not part of a portfolio
Portfolio theory
Encourages diversification of assets
Covariance and correlation measure what?
How two stocks move together
How a stock moves with the market
Covariance
Sum of prob[X - E(Rx)][Y - E(Ry)]
A negative covariance indicates what?
Stocks tend to move in opposite directions
The covariance gives a sense of what?
The magnitude and the direction of how two stocks move together
Correlation coefficients show what?
How tightly two stocks "track" each other (independent from magnitude)
The correlation coefficient falls between what two numbers ALWAYS?
-1.0 and 1.0
CorrXY = ?
CorrXY = (CovXY / sdXsdY)
sdX = ?
standard deviation of X
If CorrXY is zero, then the movements of stocks....
are unrelated to each other
Positive values of CorrXY mean what?
Stocks move in same direction
To earn rewards, you must do what?
Take risks; "be in it to win it"
Most investors like what?
Stocks with lots of return and low risk
What is one way you can lower the risk of a portfolio?
Through diversification
- By owning many stocks, if one stock does poorly, it is likely that another stock in the portfolio might do well and offset the loss
What are the most important things to know about a stock portfolio?
Return and risk!
Expected portfolio return equation:
E(Rp) = sum of W x E(R)
W = weight
E(R) = expected return
Portfolio risk is not what?
It is NOT a weighted average of the individual standard deviations of the stocks
Knowing how stocks move together is important for what?
Determining the risk of a portfolio
As covariance becomes more ______, the portfolio is made less risky:
Negative
Standard deviation equation:
the square root of the variance
Variance equation:
Wx^2sdx^2 + Wy^2sdy^2 + 2WxWyCovxy
The risk of a portfolio is less than what?
Than the risk of either stock by itself
The lower the correlation between the stocks, the lower the what?
The lower the standard deviation of the portfolio of both stocks (and lower standard deviation means lower risk)
The investor's goal is what?
To maximize return and minimize risk
- the investor can choose the weights of the different stocks in the portfolio to attain different risk-return combinations
Efficient Portfolio Frontier
What are the two types of risk?
1. Non-systematic risk
2. Systematic risk
Non-systematic risk
Risk that can be diversified away by holding a portfolio of stocks as opposed to a single stock
What are some other names for non-systematic risk?
Diversifiable risk, unique risk, company specific risk
What are some sources of non-systematic risk?
strikes, lawsuits, industrial accidents
- these are risks that may affect a single company but will not affect all firms in the economy at the same time
Why do investors not require compensation in the form of higher returns for non-systematic risk?
Because non-systematic risk can be diversified away/reduced by diversification
Systematic risk
Risk that cannot be diversified away
- most firms in the market are affected in the same way by this type of risk
What are some other names for systematic risk?
non-diversifiable risk, market risk
Why do investors require compensation for systematic risk?
Because they cannot get rid of systematic risk just by diversifying their portfolio
- the higher the level of systematic risk present, the higher the required rate of return
Rate of return
The rate that shareholders demand for an investment
Total Risk = ?
Total Risk = Systematic Risk + Non-systematic Risk
What is the standard deviation when an asset is riskless?
Standard deviation is zero
Weights always add up to ______:
1.0
When we combine a riskfree asset with a risky asset, the risk-return tradeoff is what?
A straight-line
Expected Return - Standard Deviation Graph
Any portfolio is what?
A risky asset
- a portfolio can be thought of as a risky asset just like an individual stock
How can we obtain the best expected return for any level of risk?
By combining a riskfree asset with the market portfolio
Market portfolio
A weighted combination of all risky investments weighted by their value in the overall economy
Dow Jones
The average price of 30 selected industrial stocks, used as a measure of general market trends
T or F: the Dow Jones is not a market portfolio
True
A widow/the widower curve indicates that one should invest what?
3/4 of money in risk-free assets
A young gun curve indicates that one should invest what?
3/4 in riskier assets
The new frontier that should be invested in is called....
The market portfolio (M)
For a well-diversified portfolio, the amount that X (an additional investment) contributes to the risk of the portfolio depends on what?
Only on the covariance of X with the existing portfolio
- this means we can measure risk as the covariance of an individual stock with the investor's existing portfolio
Proxy
Agent, substitute, person authorized to act on behalf of another
In finance, we typically use what as a proxy for the investor's portfolio?
Some market index, such as the S&P 500
The market index is indicated by what letter?
M
The market index M represents what?
The average investor's portfolio
What is the relevant measure of the risk of a stock?
The covariance of its return with the market index
T or F: the variance of a stock measures its risk
FALSE, the variance of a stock does not measure its risk
The more a stock covaries _______ with the market, the riskier it is:
Positively
Beta of an asset
The measure of a stock's price sensitivity to that of the market index
Beta is commonly used to measure what?
Systematic risk
- this is closely related to the covariance of the asset with the market portfolio
CovXM =
CovXM = CorrXM sdX sdM
Covariance = correlation coefficient times standard deviation of X times standard deviation of the market
Beta equation:
Bx = (Covariance of asset / variance of market)
Variance
Standard deviation squared
The systematic risk of an asset is measured by what?
The asset's Beta
Covariance can also be called what?
Correlation coefficient
If an asset's beta is 2.0, what does this mean?
That it is twice as risky as the market
ex: if S&P falls 5%, the expected decline in the stock will be 10%
A beta of 1.0 means what?
That the stock is exactly as risky as the market index
The average stock has a beta of what?
1.0 (same as market index)
The beta of a risk-free asset is ____
Zero
How can you calculate a beta?
Run a regression
- You run a regression of the returns of the stock on the returns of the market index
Rstock =
Rstock = a + b Rmarket
- the value of b is an estimate of the beta
A regression program tells you the value of what?
b (an estimate of beta)
The slope of the line on a regression graph is what?
The beta of the stock
- it tells you how far the price of the stock is expected to move if the market moves 1%
The slope is the beta of the stock. What does it tell you?
How much the stock is expected to change when market changes
What is the beta of a portfolio?
The weighted average of the betas of the individual stocks
CAPM
Capital Asset Pricing Model
- a linear model that relates risk and return
Re = Rf + Beta(Rm-Rf).
Required Return equation
Required Return = Risk-free rate + Risk premium
For a risk-free security, what is the risk premium?
Zero
What is an example of a risk-free security?
Government bill
The risk premium for a risky stock is what?
Greater than zero
How can you determine the required return?
Using CAPM
Kx = RF + Beta[E(Rm) - RF]
Kx, or the required return for asset x, can be denoted as what?
E(Rx)
- this is the expected return of asset x
What does E(Rm) indicate?
Expected return on the market index
RF = ?
Riskfree rate
If Beta = 1.0, then what does Kx equal?
Kx = E(Rm) because if the beta is 1.0, then it is exactly as risky as the market index so the expected returns will be the same
What is the risk premium?
It is the amount of return above the risk-free rate that investors demand for holding risky stocks
B[E(Rm) - RF]
What is the market risk premium?
The market risk premium is the excess return that investors require for choosing to purchase stocks over "risk-free" securities
E(Rm) - RF
Since the beta of the market is 1.0, any stock that has this beta has the market risk premium.
The graph of Kx vs. Beta is called what?
The security market line
Security market line
This tells us how the required return of an asset varies with its beta
The portfolio risk is equal to what?
The standard deviation of the portfolio
Expected return
the return on a risky asset expected in the future
MARKET EFFICIENCY
MARKET EFFICIENCY
What does market efficiency mean?
Means you get exactly what you pay for when you buy a stock