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CHAPTER 8 Ri sk and Rates of Return. Outline Stand-alone return and risk Return Expected return Stand-alone risk Portfolio return and risk Portfolio return Portfolio risk Link Risk & return: CAPM / SML Beta CAPM and computing SML. I-1: Return: What is my reward of investing?.
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CHAPTER 8Risk and Rates of Return Outline Stand-alone return and risk Return Expected return Stand-alone risk Portfolio return and risk Portfolio return Portfolio risk Link Risk & return: CAPM / SML Beta CAPM and computing SML
Investment returns If $1,000 is invested and $1,100 is returned after one year, the rate of return for this investment is: • ($1,100 - $1,000) / $1,000 = 10%. The rate of return on an investment can be calculated as follows: (Amount received – Amount invested) • Return =________________________ Amount invested
Rates of Return: stocks HPR = Holding Period Return P1 = Ending price P0 = Beginning price D1 = Dividend during period one Define return? Your gain per dollar investment
Rates of Return: Example Ending Price = 24 Beginning Price = 20 Dividend = 1 HPR = ( 24 - 20 + 1 )/ ( 20) = 25%
Calculating expected return • Two scenarios and the concept of expected return • Extending to more than two scenarios
Summary of expected returns Expected return HT 12.4% Market 10.5% USR 9.8% T-bill 5.5% Coll. 1.0% HT has the highest expected return, and appears to be the best investment alternative, but is it really? Have we failed to account for risk?
Prob. T - bill USR HT 0 5.5 9.8 12.4 Rate of Return (%) Comparing standard deviations
Comments on standard deviation as a measure of risk • Standard deviation (σi) measures total, or stand-alone, risk. • The larger σi is, the lower the probability that actual returns will be closer to expected returns. • Larger σi is associated with a wider probability distribution of returns.
Investor attitude towards risk • Risk aversion – assumes investors dislike risk and require higher rates of return to encourage them to hold riskier securities. • Risk premium – the difference between the return on a risky asset and a risk free asset, which serves as compensation for investors to hold riskier securities.
Comparing risk and return ^ * Seem out of place.
Selected Realized Returns, 1926 – 2001 Average Standard ReturnDeviation Small-company stocks 17.3% 33.2% Large-company stocks 12.7 20.2 L-T corporate bonds 6.1 8.6 Source: Based on Stocks, Bonds, Bills, and Inflation: (Valuation Edition) 2002 Yearbook (Chicago: Ibbotson Associates, 2002), 28.
Coefficient of Variation (CV) A standardized measure of dispersion about the expected value, that shows the risk per unit of return.
Risk rankings, by coefficient of variation CV T-bill 0.0 HT 1.6 Coll. 13.2 USR 1.9 Market 1.4 • Collections has the highest degree of risk per unit of return. • HT, despite having the highest standard deviation of returns, has a relatively average CV.
Portfolio construction:Risk and return Assume a two-stock portfolio is created with $50,000 invested in both HT and Collections. • Expected return of a portfolio is a weighted average of each of the component assets of the portfolio. • Standard deviation is a little more tricky and requires that a new probability distribution for the portfolio returns be devised.
An alternative method for determining portfolio expected return
Comments on portfolio risk measures • σp = 3.4% is much lower than the σi of either stock (σHT = 20.0%; σColl. = 13.2%). • σp = 3.4% is lower than the weighted average of HT and Coll.’s σ (16.6%). • Therefore, the portfolio provides the average return of component stocks, but lower than the average risk. • Why? Negative correlation between stocks.
Stock W Stock M Portfolio WM 40 15 0 0 0 -10 -10 Returns distribution for two perfectly negatively correlated stocks (ρ = -1.0) 40 40 15 15 -10
Stock M’ Portfolio MM’ Stock M 25 25 25 15 15 15 0 0 0 -10 -10 -10 Returns distribution for two perfectly positively correlated stocks (ρ = 1.0)
Creating a portfolio:Beginning with one stock and adding randomly selected stocks to portfolio • σp decreases as stocks added, because they would not be perfectly correlated with the existing portfolio. • Expected return of the portfolio would remain relatively constant. • Eventually the diversification benefits of adding more stocks dissipates (after about 10 stocks), and for large stock portfolios, σp tends to converge to 20%.
sp (%) Company-Specific Risk 35 Stand-Alone Risk, sp 20 0 Market Risk 10 20 30 40 2,000+ # Stocks in Portfolio Illustrating diversification effects of a stock portfolio
Breaking down sources of risk Stand-alone risk = Market risk + Firm-specific risk • Market risk – portion of a security’s stand-alone risk that cannot be eliminated through diversification. Measured by beta. • Firm-specific risk – portion of a security’s stand-alone risk that can be eliminated through proper diversification.
Beta • Measures a stock’s market risk, and shows a stock’s volatility relative to the market. • Indicates how risky a stock is if the stock is held in a well-diversified portfolio. • Portfolio beta is a weighted average of its individual securities’ beta
Calculating betas • Run a regression of past returns of a security against past returns on the market. • The slope of the regression line is defined as the beta coefficient for the security.
Comments on beta • If beta = 1.0, the security is just as risky as the average stock. • If beta > 1.0, the security is riskier than average. • If beta < 1.0, the security is less risky than average. • Most stocks have betas in the range of 0.5 to 1.5.
What risk do we care? • Stand alone? • Risk that can not be diversified?
Capital Asset Pricing Model (CAPM) • Model based upon concept that a stock’s required rate of return is equal to the risk-free rate of return plus a risk premium that reflects the riskiness of the stock after diversification.
Capital Asset Pricing Model (CAPM) • Model linking risk and required returns. CAPM suggests that a stock’s required return equals the risk-free return plus a risk premium that reflects the stock’s risk after diversification. ri = rRF + (rM – rRF) bi • Risk premium RP: additional return to take additional risk • The market (or equity) risk premium is (rM – rRF)
Calculating required rates of return • rHT = 5.5% + (5.0%)(1.32) = 5.5% + 6.6% = 12.10% • rM = 5.5% + (5.0%)(1.00) = 10.50% • rUSR = 5.5% + (5.0%)(0.88) = 9.90% • rT-bill = 5.5% + (5.0%)(0.00) = 5.50% • rColl = 5.5% + (5.0%)(-0.87) = 1.15%
Applying CAPM • Portfolio beta: Beta of a portfolio is a weighted average of its individual securities’ betas. • Computing other variables: risk free rate, market return, market risk premium • Computing the difference of return between two stocks. • Computing price in the future when current price is given
CAPM in a graph: the Security Market Line SML: ri = 5.5% + (5.0%) bi ri (%) SML . HT . . rM = 10.5 rRF = 5.5 . USR T-bills . Risk, bi -1 0 1 2 Coll.
Applying CAPM in real world(optional) • Total Risk vs. Beta. An experiment • The difference between commonly referred risk and beta (Are these high beta stocks really high beta) • High risk( total risk), low beta stock can hedge your portfolio (reduce portfolio risk)
Problems with CAPM (optional) • Measurement error of beta • Empirical relationship between beta and return is weak • Size and Book-to-market factors • Momentum
Optional: diversification in real world • Stock Index ETF • Style: Value vs. Growth • Style: Small vs. Big • Performance, Risk, Expense(0.1% is low, 0.5% is about average) • Examples: • Vanguard Small Cap Value ETF VBR • Small growth: VBK • Large value: VTV • Large growth: VUG
diversification in real world • Foreign ETF:RBL • Pros: • More diversification • Low PE ratio • cons • Higher risk • Higher expense: 0.6% vs. 0.1% • Higher spread • Poor prior performance