CH 13- Textbook Flashcards
to a diversified investor what sort of risks matter
systematic risk
what are the two types of risks associated with individual assets
systematic risk: affects all asssets in economy
unsystematic risk: affects small number of assets
what is the SML high level
realtionship between risk and return; it is a representation of market equilbrium
what are the states of the eocnomy
boom, recession, etc.
how do you calcualte expected reurn from a stock?
Let the stock be Stock C
E(Rc)= (prob of boom)( stock c returns in boom)+(prob of recession)(stock c return in recession)
or E(R) = sumj Rj x Pj (R=Value of jth outcome, P= prob of jth outcome)
its the sum of the possible returns
multiplied by their probabilities
How do you calculate regular riskpremium?
how do you calc projected/ expected risk preiium?
risky investment- risk free investment
expected return on a risky investment- certain return on a risk free investment
How to calculate the vriance
- get expected return
- return-expected return
- square #2
- ultiply by Probability
and then if you want SD then sqrt #4
Var= Sumj[ Rj - E(R)]^2 x Pj
SD= sqrt(var)
how to do analysis with sd, var and mean?
- which has the higher expected return?
- does this also have higher volatility? (remember you can cover 2/3 probability by adding / subtracitng one standard deviation)
what is a portfolio?
owning several stocks/bonds/assets
Portfolio weights
the amount of the total portfolio value that is invested in each portfolio asset
if you have $50 in asset A and $150 in asset B, portfolio is worht $200, and A has 25% weight and B has 75%
PORTFOLIO WEIGHT MUST ADD UP TO 1
How to calcualte portfolio returns in each state of economy
hwo to calcualte expected return of the portfolio from this?
FOR BOOM= (portfolio weight x return of asset A)+ (portfolio weight x return of Asset B)
FOR RECESSION= (portfolio weight x return of asset A)+ (portfolio weight x return of Asset B)
E(Rp)= Sum FOR BOOM + FOR RECESSION
IS Standard deviaiton of a portfolio the sum of standard deviation of all individual assets?
NO! diversifiying portoflio reduces risk!!!
this is because of correlation
positive correlation
negative correlation
0 correlation
assets A and b move together
aseets a and b move in opp directions
unrelated
what does it mean when portfolios are dominated b the min var portfolio
like a curve on the grpah, there is apoint with min variance and higher expected retunr
though you could invest 100% in these portfolios it wouldr educe the expected return and require greater variance so no one would od it
When the returns on the two assets are perfectly correlated, the portfolio standard
deviation is simply the weighted average of the individual standard deviations. In this
special case:
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With perfect correlation, all possible portfolios lie on a straight line between U and L in
expected return/standard deviation space as shown in Figure 13.4. In this polar case,
there is no benefit from diversification. But, as soon as correlation is less than perfectly
positive (CORR , < +1.0), diversification reduces risk.
As long as CORR is less than +1.0, the standard deviation of a portfolio of two securities is
less than the weighted average of the standard deviations of the individual securities.
Figure 13.4 shows this important result by graphing all possible portfolios of U and L
for the four cases for CORR given in Table 13.7. The portfolios marked 1, 2, 3, and 4
in Figure 13.4 all have an expected return of 20.91%, as calculated in Table 13.7.
*
COVL,U = CORRL,U × σL × σU
TABLE 13.7
Portfolio standard deviation and correlation
Stock L x = 2/11 σ = 45% E(R ) = 25%
Stock U x = 9/11 σ = 10% E(R ) = 20%
E(R ) = (2/11) × 25% + 9/11 × 20% = 20.91%
CORR Portfolio Standard Deviation of Portfolio σ
1. −1.0 0.0000%
2. 0.0 11.5708%
3. +0.7 15.0865%
4. +1.0 16.3636%
L L L
U U U
P
L,U P
(
2
11
× 45%) + (
9
11
× 10%) = 16. 3636%
L U
L,U
Their standard deviations also come from Table 13.7. The other points on the respective
lines or curves are derived by varying the portfolio weights for each value of CORR .
Each line or curve represents all the possible portfolios of U and L for a given correlation.
Each is called an opportunity set or feasible set. The lowest opportunity set representing
CORR = 1.0 always has the largest standard deviation for any return level. Once again,
this shows how diversification reduces risk as long as correlation is less than perfectly
positive.
While higher correlations reduce its advantages, doubts about
diversification were overstated for two reasons. First, although correlations undoubtedly increased during
the crisis, they later returned to more normal levels. Second, even with relatively high positive correlation
between assets, diversification still reduces risk as long as the correlation coefficient is less than 1.0
(perfect positive correlation).
What is total return?
expected return + unexpected return
R= E(R) +U
Announcement = expected part + surpruse
expected part= what we use to form expectation (E(r)
SURPRISE = UNEXPECTED PART
market generally already discounts for the expected part
Systematic risk:
affects lots of assets, market-wide, market risks
unsystematic risk
surprise risk, affects a single asset or a small group, unique/asset speciifc,
break down the return using systematic and unsytsematic risk
Return= exp return + systematic portion + unsystematic portion
R= E(R) + SYSTEMATIC + UNSYSTEMATIC
Systematic = m
USYSTEMATIC= e
the more stocks you have in your pprootfolio
the less risk you face in terms of standard deviation
Principle of diversificaiton
spreading an investment across many assetss elimiates some of the risk!
diversifiabel risk is
the part hta t can be elimiated by diveristiofication
Can a minimum level of risk be elimated?
not possibel simply by diversifying, min level= non diversificable risk
DIVERSIFICATION REDUCES RISK BUT ONLY TO A CERTAIN POINT