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ECON 251: Financial Theory

Lecture 22 - Risk Aversion and the Capital Asset Pricing Theorem. Until now we have ignored risk aversion. The Bernoulli brothers were the first to suggest a tractable way of representing risk aversion. They pointed out that an explanation of the St. Petersburg paradox might be that people care about expected utility instead of expected income, where utility is some concave function, such as the logarithm. One of the most famous and important models in financial economics is the Capital Asset Pricing Model, which can be derived from the hypothesis that every agent has a (different) quadratic utility. Much of the modern mutual fund industry is based on the implications of this model. The model describes what happens to prices and asset holdings in general equilibrium when the underlying risks can't be hedged in the aggregate. It turns out that the tools we developed in the beginning of this course provide an answer to this question. (from oyc.yale.edu)

Lecture 22 - Risk Aversion and the Capital Asset Pricing Theorem

Time Lecture Chapters
[00:00:00] 1. Risk Aversion
[00:03:35] 2. The Bernoulli Explanation of Risk
[00:12:38] 3. Foundations of the Capital Asset Pricing Model
[00:22:15] 4. Accounting for Risk in Prices and Asset Holdings in General Equilibrium
[00:54:11] 5. Implications of Risk in Hedging
[01:09:40] 6. Diversification in Equilibrium and Conclusion

References
Lecture 22 - Risk Aversion and the Capital Asset Pricing Theorem
Instructor: Professor John Geanakoplos. Transcript [html]. Audio [mp3]. Download Video [mov].

Go to the Course Home or watch other lectures:

Lecture 01 - Why Finance?
Lecture 02 - Utilities, Endowments, and Equilibrium
Lecture 03 - Computing Equilibrium
Lecture 04 - Efficiency, Assets, and Time
Lecture 05 - Present Value Prices and the Real Rate of Interest
Lecture 06 - Irving Fisher's Impatience Theory of Interest
Lecture 07 - Shakespeare's Merchant of Venice and Collateral, Present Value and the Vocabulary of Finance
Lecture 08 - How a Long-Lived Institution Figures an Annual Budget; Yield
Lecture 09 - Yield Curve Arbitrage
Lecture 10 - Dynamic Present Value
Lecture 11 - Social Security
Lecture 12 - Overlapping Generations Models of the Economy
Lecture 13 - Demography and Asset Pricing: Will the Stock Market Decline when the Baby Boomers Retire?
Lecture 14 - Quantifying Uncertainty and Risk
Lecture 15 - Uncertainty and the Rational Expectations Hypothesis
Lecture 16 - Backward Induction and Optimal Stopping Times
Lecture 17 - Callable Bonds and the Mortgage Prepayment Option
Lecture 18 - Modeling Mortgage Prepayments and Valuing Mortgages
Lecture 19 - History of the Mortgage Market: A Personal Narrative
Lecture 20 - Dynamic Hedging
Lecture 21 - Dynamic Hedging and Average Life
Lecture 22 - Risk Aversion and the Capital Asset Pricing Theorem
Lecture 23 - The Mutual Fund Theorem and Covariance Pricing Theorems
Lecture 24 - Risk, Return, and Social Security
Lecture 25 - The Leverage Cycle and the Subprime Mortgage Crisis
Lecture 26 - The Leverage Cycle and Crashes