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Present Value Prices and the Real Rate of Interest

By John Geanakoplos - Yale
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Lecture Description

Philosophers and theologians have railed against interest for thousands of years. But that is because they didn't understand what causes interest. Irving Fisher built a model of financial equilibrium on top of general equilibrium (GE) by introducing time and assets into the GE model. He saw that trade between apples today and apples next year is completely analogous to trade between apples and oranges today. Similarly he saw that in a world without uncertainty, assets like stocks and bonds are significant only for the dividends they pay in the future, just like an endowment of multiple goods. With these insights Fisher was able to show that he could solve his model of financial equilibrium for interest rates, present value prices, asset prices, and allocations with precisely the same techniques we used to solve for general equilibrium. He concluded that the real rate of interest is a relative price, and just like any other relative price, is determined by market participants' preferences and endowments, an insight that runs counter to the intuitions held by philosophers throughout much of human history. His theory did not explain the nominal rate of interest or inflation, but only their ratio.

Course Description

Course Index

  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. Collateral, Present Value and the Vocabulary of Finance
  8. Budgeting for a Long-Lived Institution, Yield
  9. Dynamic Present Value
  10. Social Security
  11. Overlapping Generations Models of the Economy
  12. Demography and Asset Pricing
  13. Quantifying Uncertainty and Risk
  14. Uncertainty and the Rational Expectations Hypothesis
  15. Backward Induction and Optimal Stopping Times
  16. Callable Bonds and the Mortgage Prepayment Option
  17. Modeling Mortgage Prepayments and Valuing Mortgages
  18. History of the Mortgage Market: A Personal Narrative
  19. Dynamic Hedging
  20. Dynamic Hedging and Average Life
  21. Risk Aversion and the Capital Asset Pricing Theorem
  22. The Mutual Fund Theorem and Covariance Pricing Theorems
  23. Risk, Return, and Social Security
  24. The Leverage Cycle and the Subprime Mortgage Crisis
  25. The Leverage Cycle and Crashes