528 Chapter 16
CASE STUDY FOR CHAPTER 16
Stock-Price Beta Estimation for Google, Inc.
Statisticians use the Greek letter beta to signify the slope coefficient in a linear relation. Financial
economists use this same Greek letter β to signify stock-price risk because betas are the slope
where Rit is the rate of return on an individual security i during period t, the intercept term is
described by the Greek letter α (alpha), the slope coefficient is the Greek letter β (beta) and signifies
systematic risk (as before), and the random disturbance or error term is depicted by the Greek letter
ε (epsilon). At any point in time, the random disturbance term ε has an expected value of zero, and
capital market, the CAPM asserts that investor rates of return would be solely determined by
systematic risk and both alpha and epsilon would equal zero, α = ε = 0.
As shown in Figure 16.8, managers and investors can estimate beta for individual stocks by
using a simple ordinary least-squares regression model. In this simple regression model, the
dependent Y-variable is the rate of return on an individual stock, and the independent X-variable is
than the Nasdaq market during this period. During a week when the Nasdaq market rose by 1
percent, GOOG rose by 0.9588 percent; during a week when the Nasdaq market fell by 1 percent,