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Video 2. Asset Pricing Theory in One Lecture Eric Falkenstein. MBA Course in 45 Minutes. Capital Asset Pricing Model (CAPM) Arbitrage Pricing Model (APT) Stochastic Discount Factor Model (SDF) General Equilibrium Theory. What Causes Profits? What Causes Returns? Puzzle. Monopoly power
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Video 2 Asset Pricing Theory in One Lecture Eric Falkenstein Finding Alpha
MBA Course in 45 Minutes • Capital Asset Pricing Model (CAPM) • Arbitrage Pricing Model (APT) • Stochastic Discount Factor Model (SDF) • General Equilibrium Theory Finding Alpha
What Causes Profits? What Causes Returns? Puzzle. • Monopoly power • Uncertainty (Frank Knight) • Entrepreneur (Schumpeter) • Return on Capital • Profits should go to zero over time (Das Kapital) • Modern Portfolio Theory: Return for bearing ‘risk’ Finding Alpha
Two Basic Ideas • Diversification, Diminishing Marginal Utility • Processes: • Arbitrage • Equilibrium E[Reti]=+Eif Portfolio Vol Utility Consumption # assets Decreasing marginal utility Diversification Finding Alpha
Marginal Utility St. Petersburg Paradox (1738): what is value of $1 paid if you get a head in a coin flip, where the payoff is (number of times coin flipped)^2? Should be infinity Why not? Diminishing marginal returns Finding Alpha
Marginal Revolution 1860s • Jevons, Menger, Walras noted diminishing marginal utility could explain pricing Finding Alpha
Diminishing Marginal Utility Necessary and Sufficient Condition for Risk Aversion Johnny Von Neumann and Oscar Mortgenstern 1941 Theory of Games Milton Friedman and Savage 1947 Finding Alpha
Markowitz • Why not put all your wealth in one stock? • “To suppose that safety-first consists in having a small gamble in a large number of different [companies] … strikes me as a travesty of investment policy.” Keynes Finding Alpha
Law of Large Numbers Finding Alpha
Convex Hull of Investment Possibilities Finding Alpha
Only Covariance Matters for large portfolios Total risk; U Idiosyncratic Risk Systematic Risk n Finding Alpha
Markowitz: Should Invest in Portfolios, not single asets ‘risk’ is ‘variance of return’ Finding Alpha
Why utility cares about variance, not volatility Finding Alpha
Iso-Utility Curves for Return and Volatility Finding Alpha
Why we like efficient portfolios No points plot above the red line 100% investment in security with highest E(R) Expected Return All portfolios on the red line are efficient 100% investment in minimum variance portfolio Standard Deviation Finding Alpha
'New' ideas there from start • Portfolio Selection: Efficient Diversification of Investments (1959) • Markowitz preferred ‘semi-variance’ in book • Also examines: • standard deviation, • expected value of loss, • expected absolute deviation, • probability of loss, • maximum loss • ‘Prospect Theory’ in 1952 Finding Alpha
Normality? • Levy and Markowitz (1979) show the mean-variance optimization is an excellent approximation to expected utility when not-normal • ”[in the 1960s] there was lots of interest in this issue for about ten years. Then academics lost interest. “ Eugene Fama
Tobin: Two-Fund Separation Theorem Exp Return Port-1 U1 U2 Port-2 U3 U4 Port-3 Volatility Finding Alpha
There exists a unique portfolio of risky assets that maximizes utility Finding Alpha
Regardless of risk preference, everyone uses same risky portfolio Finding Alpha
Always hold some cash: liquidity preference Expected Return C B Rf A Standard Deviation Finding Alpha
Sharpe: How do asset returns relate to efficient frontier? Finding Alpha
The Capital Asset Pricing Model Finding Alpha
Security Market Line (SML) Market Portfolio Expected Return E(R) Rf 1.0 Beta Finding Alpha
General Equilibrium aka Stochastic Discount Factor CAPM Finding Alpha
APT and SDF: use similar logic to generate arbitrary factors Total Ut Marginal Ut Wealth T-bills, MT Tbonds, LT Treasuries, Corp Bonds, Mortgages, Large Cap Stocks, Large-cap growth stocks, medium cap stocks, small cap stocks, non-US bonds, European stocks, Japanese stocks Finding Alpha
Arbitrage Pricing Theory • If f is a risk factor, it must have a linear price to prevent arbitrage • Can of beer: $1 • 6-pack of beer: $6 • Case of beer (24 pack): $24 • Price of beer linear in units, else arbitrage Finding Alpha
APT and Behavioral Finance • For k number factors • How many factors? 3? 5? 12? • What are the factors? Empirical issue. • Could be estimated just like a ‘bias’ • Total Portfolio Volatility no longer the issue Finding Alpha
Asset Pricing Theory • Markowitz. Normative model: people should invest in efficient portfolios • No residual aka idiosyncratic aka unsystematic, volatility • Tobin: Efficient portfolio always combination of a single risky portfolio and the non-risky asset • Sharpe : Given Tobin, covariance with the market dictate expected return • Ross: add factors like Rm-Rf , whatever matters to people, linear pricing in factors Finding Alpha
Hope for Final Theory • linear in risk factors • not include residual risk • include something very like the stock market as one of the prominent factors Finding Alpha