This lecture gives a brief history of the young field of financial theory, which began in business schools quite separate from economics, and of my growing interest in the field and in Wall Street. A cornerstone of standard financial theory is the efficient markets hypothesis, but that has been discredited by the financial crisis of […]

# Financial Theory - Video Series

## Utilities, Endowments, and Equilibrium

This lecture explains what an economic model is, and why it allows for counterfactual reasoning and often yields paradoxical conclusions. Typically, equilibrium is defined as the solution to a system of simultaneous equations. The most important economic model is that of supply and demand in one market, which was understood to some extent by the […]

## Computing Equilibrium

Our understanding of the economy will be more tangible and vivid if we can in principle explain all the economic decisions of every agent in the economy. This lecture demonstrates, with two examples, how the theory lets us calculate equilibrium prices and allocations in a simple economy, either by hand or using a computer. In […]

## Efficiency, Assets, and Time

Over time, economists’ justifications for why free markets are a good thing have changed. In the first few classes, we saw how under some conditions, the competitive allocation maximizes the sum of agents’ utilities. When it was found that this property didn’t hold generally, the idea of Pareto efficiency was developed. This class reviews two […]

## Present Value Prices and the Real Rate of Interest

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 […]

## Irving Fisher’s Impatience Theory of Interest

Building on the general equilibrium setup solved in the last week, this lecture looks in depth at the relationships between productivity, patience, prices, allocations, and nominal and real interest rates. The solutions to three of Fisher’s famous examples are given: What happens to interest rates when people become more or less patient? What happens when […]

## Shakespeare’s Merchant of Venice and Collateral, Present Value and the Vocabulary of Finance

While economists didn’t have a good theory of interest until Irving Fisher came along, and didn’t understand the role of collateral until even later, Shakespeare understood many of these things hundreds of years earlier. The first half of this lecture examines Shakespeare’s economic insights in depth, and sees how they sometimes prefigured or even surpassed […]

## How a Long-Lived Institution Figures an Annual Budget Yield

In the 1990s, Yale discovered that it was faced with a deferred maintenance problem: the university hadn’t properly planned for important renovations in many buildings. A large, one-time expenditure would be needed. How should Yale have covered these expenses? This lecture begins by applying the lessons learned so far to show why Yale’s initial forecast […]

## Yield Curve Arbitrage

Where can you find the market rates of interest (or equivalently the zero coupon bond prices) for every maturity? This lecture shows how to infer them from the prices of Treasury bonds of every maturity, first using the method of replication, and again using the principle of duality. Treasury bond prices, or at least Treasury […]

## Dynamic Present Value

In this lecture we move from present values to dynamic present values. If interest rates evolve along the forward curve, then the present value of the remaining cash flows of any instrument will evolve in a predictable trajectory. The fastest way to compute these is by backward induction. Dynamic present values help us understand the […]