Forces That Move Stock Prices

Stock prices are determined in the marketplace, where seller supply meets buyer demand. There is no clean equation that tells us exactly how a stock price will behave, but we do know a few things about the forces that move a stock up or down. These forces fall into three categories: fundamental factors, technical factors and market sentiment.

Fundamental Factors

In an efficient market, stock prices would be determined primarily by fundamentals, which, at the basic level, refer to a combination of two things:

1) An earnings base (earings per share (EPS), for example) and

2) a valuation multiple (a P/E ratio, for example).

An owner of a common stock has a claim on earnings, and earnings per share (EPS) is the owner's return on his or her investment. When you buy a stock, you are purchasing a proportional share of an entire future stream of earnings. That's the reason for the valuation multiple: it is the price you are willing to pay for the future stream of earnings.

Part of these earnings may be distributed as dividends, while the remainder will be retained by the company (on your behalf) for reinvestment. We can think of the future earnings stream as a function of both the current level of earnings and the expected growth in this earnings base.

As shown in the diagram, the valuation multiple (P/E), or the stock price as some multiple of EPS, is a way of representing the discounted present value of the anticipated future earnings stream.

About the Earnings Base

Although we are using EPS, an accounting measure, to illustrate the concept of earnings base, there are other measures of earnings power. Many argue that cash-flow based measures are superior. For example, free cash flow per share is used as an alternative measure of earnings power.

The way earnings power is measured may also depend on the type of company. Many industries have their own tailored metrics. Real estate investment trusts (REITs), for example, use a special measure of earnings power called funds from operations (FFO). Relatively mature companies are often measured by dividends per share, which represents what the shareholder actually receives.

About the Valuation Multiple

The valuation multiple expresses expectations about the future. As we already explained, it is fundamentally based on the discounted present value of the future earnings stream. Therefore, the two key factors here are

1) the expected growth in the earnings base, and

2) the discount rate, which is used to calculate the present value of the future stream of earnings.

A higher growth rate will earn the stock a higher multiple, but a higher discount rate will earn a lower multiple.

What determines the discount rate? First, it is a function of perceived risk. A riskier stock earns a higher discount rate, which in turn earns a lower multiple. Second, it is a function of inflation (or interest rates, arguably). Higher inflation earns a higher discount rate, which earns a lower multiple (meaning the future earnings are worth less in inflationary environments).

In summary, the key fundamental factors are:

The level of the earnings base (represented by measures such as EPS, cash flow per share, dividends per share)

The expected growth in the earnings base

The discount rate, which is itself a function of inflation

The perceived risk of the stock.