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Risk and Return Professor Thomas Chemmanur
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22 1. Risk Aversion ASSET – A: EXPECTED PAYOFF = 0.5(100) + 0.5(1) = $50.50 ASSET – B:PAYS $50.50 FOR SURE WHICH ASSET WILL A RISK AVERSE INVESTOR CHOOSE? RISK NEUTRAL INVESTORS INDIFFERENT BETWEEN A AND B. RISK LOVING? PROB = 0.5 $100 $1
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33 Certainty Equivalent THE CERTAINTY EQUIVALENT OF A RISK AVERSE INVESTOR THE AMOUNT HE OR SHE WILL ACCEPT FOR SURE INSTEAD OF A RISKY ASSET. THE MORE RISK-AVERSE THE INVESTOR, THE LOWER HIS CERTAINTY EQUIVALENT. RETURN FROM ANY ASSET P e = END OF PERIOD PRICE P b = BEGINNING OF PERIOD PRICE D = CASH DISTRIBUTIONS DURING THE PERIOD
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44 EXPECTED UTILITY MAXIMIZATION IF RETURNS ARE NORMALLY DISTRIBUTED, RISK- AVERSE INDIVIDUALS CAN MAXIMIZE EXPECTED UTILITY BASED ONLY ON THE MEAN, VARIANCE, AND COVARIANCE BETWEEN ASSET RETURNS. PROBLEM STATEPROB KELLY Vs. WATER (S) (p s ) PROD (r 1S ) (r 2S ) BOOM 0.3 100%10% NORMAL 0.4 15%15% RECESSION 0.3 -70%20%
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55 Solution to Problem EXPECTED RETURN VARIANCE,
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66 Solution to Problem STANDARD DEVIATION, SIMILARLY,
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77 Solution to Problem COVARIANCE BETWEEN ASSETS 1 & 2 = 0.3(100-15)(10-15) + 0.4(15-15)* (15-15) +0.3(-70-15)(20-15) = -255(%) 2 CORRELATION CO-EFFICIENT
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88 Solution to Problem PORTFOLIO MEAN AND VARIANCE PORTFOLIO WEIGHTS X i, i = 1,…, N. X 1 = 0.5 OR 50% X 2 = 0.5 OR 50% = 0.5(15) + 0.5(15) = 15% = 0.5 2 (4335) + 0.5 2 (15) + 2(0.5)(0.5)(-255) = 960(%) 2
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99 Choosing Optimal Portfolios IN A MEAN-VARIANCE FRAMEWORK, THE OBJECTIVE OF INDIVIDUALS WILL BE MAXIMIZE THEIR EXPECTED RETURN, WHILE MAKING SURE THAT THE VARIANCE OF THEIR PORTFOLIO RETURN (RISK) DOES NOT EXCEED A CERTAIN LEVEL. 1,2 = -1 PERFECTLY NEGATIVELY CORRELATED RETURNS 1,2 = +1PERFECTLY POSITIVELY CORRELATED RETURNS -1 1,2 +1 MOST STOCKS HAVE POSITIVELY CORRELATED (IMPERFECTLY) RETURNS.
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10 Optimal Two-Asset Portfolios CASE (1)
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11 Optimal Two-Asset Portfolios CASE (2)
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12 Optimal Two-Asset Portfolios CASE (3) DIVERSIFICATION IS POSSIBLE ONLY IF THE TWO ASSET RETURNS ARE LESS THAN PERFECTLY POSITIVELY CORRELATED.
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13 MEAN AND VARIANCE OF AN N-ASSET PORTFOLIO IF N = 3 NOTE THAT
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14 PROBLEM – 1
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15 PROBLEM – 1
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16 RISKY ASSETS WITH LENDING AND BORROWING NOTE THAT, FOR THE RISK-FREE ASSET, F = 0. FURTHER, WHILE “LENDING” IMPLIES THAT X F > 0, “BORROWING” IMPLIES THAT X F < 0. PROBLEM – 2 (A)
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17 PROBLEM – 2 (B) SINCE YOU ARE BORROWING AN AMOUNT EQUAL TO YOUR WEALTH W AT THE RISK-FREE RATE, NOTICE THAT
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18 OPTIMAL PORTFOLIO CHOICE BY MV INVESTORS PICK x 1, x 2, ….., x N TO SUBJECT TO THE RESTRICTIONS: (CANNOT INVEST MORE THAN AVAILABLE WEALTH, INCLUDING BORROWING, ETC.)
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19 OPTIMAL PORTFOLIO CHOICE BY MV INVESTORS SOLUTION WITH NO RISK-FREE ASSET NOT ALL INVESTORS WILL CHOOSE TO HOLD THE MINIMUM VARIANCE PORTFOLIO. THE PRECISE LOCATION OF AN INVESTOR ON THE EFFICIENT FRONTIER DEPENDS ON THE RISK σ P HE IS WILLING TO TAKE. * * * * * * * * * EFFICIENT FRONTIER
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20 OPTIMAL PORTFOLIO CHOICE BY MV INVESTORS SOLUTION WITH RISK FREE LENDING / BORROWING THE SET OF RETURNS YOU CAN GENERATE BY COMBINING A RISK-FREE AND RISKY ASSET LIES ON THE STRAIGHT LINE JOINING THE TWO TO GO ON THE LINE SEGMENT MT, AN INVESTOR WILL BORROW AT THE RISK-FREE RATE r F. M * T EFFICIENT SET IS THE STRAIGHT LINE: r F MT
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21 OPTIMAL PORTFOLIO CHOICE BY MV INVESTORS WHEN INVESTORS AGREE ON THE PROBABILITY DISTRIBUTION OF THE RETURNS OF ALL ASSETS: MARKET EQUILIBRIBUM IF INVESTORS AGREE ON THE DISTRIBUTIONS OF ALL ASSETS RETURNS, THEY WILL AGREE ON THE COMPOSITION OF THE PORTFOLIO M: THE “MARKET PORTFOLIO”. IN SUCH A WORLD, INVESTORS WILL ALL INVEST THEIR WEALTH BETWEEN TWO PORTFOLIOS THE RISK-FREE ASSET AND THE MARKET PORTFOLIO. THE MARKET PORTFOLIO IS THE PORTFOLIO OF ALL RISKY ASSETS IN THE ECONOMY, WEIGHTED IN PROPORTION TO THEIR MARKET VALUE.
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22 RISK OF A WELL-DIVERSIFIED PORTFOLIO WHAT HAPPENS WHEN YOU INCREASE THE NUMBER OF STOCKS IN A PORTFOLIO? IT CAN BE SHOWN THAT THE TOTAL PORTFOLIO VARIANCE GOES TOWARD THE AVERAGE COVARIANCE BETWEEN TWO STOCKS AS N No. of Assets in a Portfolio PP
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23 SYSTEMATIC AND UNSYSTEMATIC RISK SYSTEMATIC RISK: THIS IS RISK WHICH AFFECTS A LARGE NUMBER OF ASSETS TO A GREATER OR LESSER DEGREE THEREFORE, IT IS RISK THAT CANNOT BE DIVERSIFIED AWAY E.G. RISK OF ECONOMIC DOWNTURN WITH OIL PRICE INCREASE UNSYSTEMATIC RISK: RISK THAT SPECIFICALLY AFFECTS A SINGLE ASSET OR SMALL GROUP OF ASSETS CAN BE DIVERSIFIED AWAY E.G. STRIKE IN A FIRM, DEATH OF A CEO, INCREASE IN RAW MATERIALS PRICE
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24 SYSTEMATIC AND UNSYSTEMATIC RISK TOTAL RISK ( 2 OR ) = SYSTEMATIC (ß OR im / m 2 ) + UNSYSTEMATIC RISK SINCE UNSYSTEMATIC RISK IS DIVERSIFIABLE, ONLY SYSTEMATIC OR MARKET RISK IS “PRICED” i IS THE APPROPRIATE MEASURE OF SYSTEMATIC RISK
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25 THE CAPITAL ASSET PRICING MODEL i : BETA OF i th STOCK SECURITY MARKET LINE m = 1 RFRF
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26 APPLICATION OF THE CAPM 1. IN ESTIMATING THE COST OF CAPITAL FOR A FIRM 2. AS A BENCHMARK IN PORTFOLIO PERFORMANCE MEASUREMENT PROBLEM – 3 SECURITY MARKET LINE: STOCK 1: STOCK 2:
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27 Problem 3 PROBLEM 4
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28 Problem 4 SUBTRACTING (1) FROM (2), FROM (1),
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29 ESTIMATING BETA WE CAN ESTIMATE BETA FOR EACH STOCK BY FITTING ITS RETURN OVER TIME AGAINST THE RETURN OF THE MARKET PORTFOLIO (S&P 500 INDEX), USING LINEAR REGRESSION (USE EXCEL TO DO THIS): ERROR TERM: u it “BEST” STRAIGHT LINE THAT EXPLAINS THE DATA SLOPE = i
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