Fundamentals of Financial Instruments, 2nd Edition

CHAPTER 2Mathematics of Finance

INTEREST RATES

Interest on money borrowed and lent is a feature of our daily lives. Most people have paid and received interest at some point in time. It is a common practice to make investments by buying bonds and debentures, and opening checking, savings, and time deposits with institutions like commercial banks. Bonds and debentures pay interest on their face value or principal. We refer to this as the coupon. Banks, while they do not pay interest on checking accounts, pay interest on savings and time deposits.

In today's consumer-driven economy, it is also a common practice to buy products and services on loan. Borrowing to buy residential property, which is referred to as a mortgage loan, is a major component of the debt taken by individuals and families. People also borrow to fund their academic pursuits in the form of student loans. Retail borrowing to finance various purchases such as automobiles and consumer durables (white goods) is a feature of today's society.

Interest may be construed as the compensation that a lender of capital receives. Why should a lender charge for making a loan? In other words, why not give an interest-free loan? It must be remembered that if you part with your money in order to extend a loan, then you are deprived of an opportunity to use the funds while they are on loan. The interest that you charge is consequently a compensation for this lost opportunity. In economic parlance we would term this as rent. Capital ...