The S&P 500 Index tracks the overall movement of the stock market by considering the stock prices of 500 large corporations. The file Stock Prices contains weekly data for this index as well as the daily closing stock prices for three companies from January 2, 2009, to December 28, 2009. The following variables are included:
WEEK- Week ending on date given
S&P- Weekly closing value for the S&P 500 Index
GE- Weekly closing stock price for General Electric
DISC- Weekly closing stock price for Discovery Communications
AAPL- Weekly closing stock price for Apple
a. Construct time-series plots for the weekly closing values of the S&P 500 Index, General Electric, Discovery, and Apple.
b. Explain any patterns present in the plots.