This lecture is about optimal exercise strategies for callable bonds, which are bonds bundled with an option that allows the borrower to pay back the loan early, if she chooses. Using backward induction, we calculate the borrower's optimal strategy and the value of the option. As with the simple examples in the previous lecture, the option value turns out to be very large. The most important callable bond is the fixed rate amortizing mortgage; calling a mortgage means prepaying your remaining balance. We examine how high bankers must set the mortgage rate in order to compensate for the prepayment option they give homeowners. Looking at data on mortgage rates we see that mortgage borrowers often fail to prepay optimally.

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

This course attempts to explain the role and the importance of the financial system in the global economy. Rather than separating off the financial world from the rest of the economy, financial equilibrium is studied as an extension of economic equilibrium. The course also gives a picture of the kind of thinking and analysis done by hedge funds.

Course Structure:
This Yale College course, taught on campus twice per week for 75 minutes, was recorded for Open Yale Courses in Fall 2009.