3. The Stock Market and Movements in Stock Prices
Firms, unlike the government, receive some of their financing from sources other than debt. Firms can
either earn money (internal finance) or sell shares of ownership known as stock (external finance).
Investors buy stocks hoping the fractional ownership will increase in value as the firm prospers and stocks
also pay cash distributions known as dividends.
Stock prices, much like bonds, should be equal to the present value of all future cash flows. The future
cash flows are dividends and a future selling price. The rate of return used to discount the cash flows can
vary depending on risk and also market rates of interest. So, in the real world, a stock’s value is dependent
on future cash flows and the discount rate. Both of those factors can and do change periodically causing
constant revaluation of a stock.
One valuation model assumes infinite holding periods and values the stock as simply the present value of
all future dividends and it assumes the stock is not sold.
4. Risk, Bubbles, Fads, and Asset Prices
Stock prices change in value according to changes in expected future returns and perceived risk. And,
given the risk premium (x) is not constant, valuation shifts accordingly. For this reason, stock prices are
reasonably volatile.
At times stock prices deviate from their fundamental value which is defined as the present value of all
future dividends. Sometimes investors are willing to pay more for a stock than it is truly worth based on
their expectations. In other words, a stock price may increase above its fundamental value simply because
investors expect it to go up. This type of price movement is dubbed rational speculative bubbles.
At other times investors respond to fads and bid stock prices higher. Fads can occur in many markets,
including housing and stocks. See the Focus box on page 385 for a classic case of an asset bubble in the
tulip bulb market in the 1600s.
V. PEDAGOGY
This chapter marries two issues: the distinction between real and nominal interest rates and the calculation
of expected present discounted values. Depending upon the focus of the course, instructors could make
the distinction between real and nominal interest rates and ignore the mathematics of present values. It is
also possible to discuss the effects of expected future policies (Chapter 16) without a full presentation of
present value. In this context, instructors could describe informally how consumption and investment
decisions (examined in Chapter 15) depend upon current and expected future income and interest rates.
VI. EXTENSIONS
The presentation of present value in the text can be applied to numerous concepts in the students’ personal
lives. Taking a few minutes to go over some of these applications can help them understand present
values better. Alternatively, instructors might want to explain informally that attitudes toward risk affect
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