When you save, you have a choice between investing in a risky asset like a stock or a safe asset like a bank account. When you borrow, there is much less choice. Usually, you just borrow at a nominal interest rate, paying back 10% regardless of the return on the stock market or the level of inflation. The only exception I can think of is the variable-rate mortgage, which at least varies with the nominal interest rate.
Why is that? We can imagine a person being able to borrow at a lower interest rate if he agrees to bear risk. His interest rate could be 20% minus the return on the stock market, for example. If the average stock market return is 6%, his average interest rate would be 14% then. Someone who wanted a safe interest rate could borrow at 16% instead.
Our borrower would be hedging someone else against stock market risk. This would be useful if the borrower were less risk averse than some saver.
Yet we don't see that. Is it because borrowers are usually more risk averse than savers? Is it because borrowers are too likely to default if they have a risky payment to make?
October 21. At lunch I figured out a new twist. Suppose I want to borrow $100 for consumption, and I am risk-loving. I could borrow an extra $50, and invest it in the stock market. That way, I have to pay back $150 in cash, but my later wealth will be $(150-value of stocks I bought) lower as a result. Thus, even a poor person could take on risk if it weren't for the possibility of going bankrupt.
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