Risk refers to the uncertainty of the future outcomes of an investment
Probability
The likelihood of an outcome
The sum of the probabilities of all the possible outcomes is equal to 1.0
Risk of expected return
The degree of uncertainty that actual return will be different from the expected return
Expected Return
1. ∑(Pt*Rt)
2. Where Pt = probability for possible return i at time t
3. Rt = possible return i at time t
Excess Return
Rt - rf
Risk Premium
E[Rt] - rf
Mean
μt ≡ E[Rt]
Variance
σt^2 ≡ E[(Rt - μt)^2]
Median
50th percentile (probability of 1/2 that Rt< median)
Skewness
Measure of the asymmetry of the distribution
Correlation
How closely two variables move together
Normal distribution is a bell-shaped, symmetric distribution
Central Limit Theorem states that the sum of independent random variables will be normally distributed
If R is normally distributed, then 68% of observations fall within +/- 1.00 std. deviations from mean, 90% within +/- 1.65 std. deviations, 95% within +/- 1.96 std. deviations, and 99% within +/- 2.58 std. deviations
Real interest rate has been slightly positive on average
Return on more risky assets has been higher on average than return on less risky assets
Returns on risk assets can be highly correlated to each other
Returns on risky assets are (usually) serially uncorrelated
Basic statistics, U.S, 1946-2001 (monthly, in percent)
Inflation
Tbill (1 yr)
Tnote (10 yr)
VW stock index
EW stock index
Motorola
The stock market was not bad because there was no FEAR!
The risk/reward relationship seems to apply over long periods
Anomalies exist in the stock market, such as the size effect, January effect, value premium, and momentum
Financial assets
Sovereign bonds
Corporate bonds
Structured financial instruments
Derivatives
Alternative investments
Hedge funds
Private investment vehicles that manage portfolios of securities and derivative positions using a variety of strategies, often with long and short positions and high leverage
Venture capital and private equity
Investing in private companies, either startups or established, that are not listed on a public exchange
Real estate investment
May be in building and/or land, either directly or indirectly through securitizations and investment funds
Commodities investment
May be in physical commodity products or through derivative products and commodity indexes
Infrastructure investment
Capital-intensive, long-lived, real assets that provide essential public services, often through public-private partnerships
Passion investments
Non-traditional assets that allow enjoyment of ownership, such as fine wine, art, antiques, and collectibles
The standard deviation of returns for the overall stock market is 4.5% monthly (16.4% annually)
The average monthly standard deviation of an individual stock is around 17% (50% annually)
Stocks tend to move together over time, but the correlation is far from perfect
Stock returns are nearly unpredictable
Market volatility changes over time, with the standard deviation of monthly returns varying from roughly 2% to 20%
Financial ratios like P/E ratios vary widely over time
Different financial assets have different risk levels